ININCJDKOTL 


MINE    TIMBERING 


MINE   TIMBERING 


BY 

WILBUR    E.    SANDERS 
BERNARD  MAcDONALD 
NORMAN     W.     PARLEE 
AND    OTHERS 


i 


NEW  YORK  AND  LONDON 

HILL    PUBLISHING    COMPANY 

1907 


COPYRIGHT,  1907,  BY  HILL  PUBLISHING  Co. 

ENTERED   AT   STATIONERS'    HALL 


The  Plimpton  Press  Norwood  Mass.  U.S.A. 


PREFACE 

THIS  book  is  a  collection  of  articles  that  have  previously 
been  printed  in  the  Engineering  and  Mining  Journal,  The  Mineral 
Industry,  and  the  transactions  of  various  societies,  the  source 
being  stated  in  a  foot-note  to  each  article.  The  article  by  Mr. 
MacDonald  was  published  originally  in  the  Proceedings  of  the 
Canadian  Mining  Institute,  and  that  by  Mr.  Parlee  in  the  Pro- 
ceedings of  the  Canadian  Society  of  Civil  Engineers.  Permission 
to  make  this  republication  has  been  courteously  granted  by  the 
Secretaries  of  both  those  societies,  and  the  respective  authors 
have  cooperated  with  suggestions  and  in  the  reading  of  proof. 
The  last  part  of  the  book  is  made  up  chiefly  of  articles  that  have 
appeared  in  the  Engineering  and  Mining  Journal  during  the  last 
two  or  three  years.  In  the  absence  of  any  treatise  on  this  impor- 
tant subject,  which  in  the  hand-books  and  text-books  on  mining 
is  dealt  with  only  in  a  superficial  way,  it  has  appeared  worth 
while  to  make  the  present  collection,  which  is  offered  not  as  a 
complete  treatise  on  the  subject,  but  rather  as  a  series  of  essays 
which  go  fully  into  many  important  details.  It  is  hoped  that  a 
thorough  and  systematic  treatise  on  mine  timbering  will  soon  be 
written.  EDITOR. 


390350 


TABLE    OF   CONTENTS 


PREFACE     ..... 
LIST  OF  ILLUSTRATIONS 


MINE  TIMBERING,  BY  WILBUR  E.  SANDERS 

Timbering  of  shafts,  stations,  and  levels,  7.  Shafts,  7.  In- 
clined shafts,  10.  Stations  for  inclines,  13.  Alinement  of 
incline  sets,  14.  Vertical  shafts,  16.  Cribbed  shaft  timber- 
ing, 16.  Halved  framing  for  shaft  sets,  18.  Square-set  shaft 
timbers,  20.  One-compartment  shafts,  20.  Locating  shaft 
sets,  22.  Alinement  of  vertical  shafts,  24.  Repairing  shafts 
25.  Timbering  shafts  in  loose  ground,  26.  Timbering  shafts 
in  running  ground,  26.  Two-compartment  shafts,  28.  Three- 
compartment  shafts,  29.  Four-compartment  shafts,  31.  Lad- 
ders, 34.  Shaft  station  sets,  35.  Stations,  35.  Levels,  36. 
Timbering  levels  in  loose  ground,  39.  Timbering  of  the  work- 
ing places  in  a  mine,  41.  Posts,  41.  Cribs,  41.  Stulls,  42. 
Penning,  45.  Square  sets  in  stoping,  46.  Reinforcing 
sets,  49.  Ore  chutes,  49.  Waste  filling,  50.  Methods  of 
framing,  50. 

MINE  TIMBERING  BY  THE  SQUARE-SET  SYSTEM  AT  ROSSLAND,  B.C., 

BY  BERNARD  MACDONALD 

Historical,  55.  Vein  characteristics  at  Rossland,  56.  Pre- 
liminary work,  56.  Sill-floor  construction,  57.  Timbers  and 
methods  used  after  sill  floor  is  laid,  60.  Per  tonnage  cost  of 
square-set  timbering,  64.  Cost  data  per  square  set,  hand 
framed,  64.  Incidental  costs,  67.  Limitations  of  the  square 
set,  67.  Reinforcement  methods,  68.  Angle  bracing,  68. 
Cribbing,  68.  Bulkheading,  70.  Filling,  70.  General  re- 
marks, 70. 

METHODS  OF  MINING  AND  TIMBERING  IN  LARGE  OREBODIES  IN 
BRITISH  COLUMBIA  AND  MICHIGAN,  BY  NORMAN  W.  PAR- 
LEE  

Le  Roi  mine,  Rossland,  B.C.,  76.  Old  Ironsides  mine, 
Phoenix,  B.C.,  85.  Baltic  mine,  Baltic,  Mich.,  89.  Atlantic 

vii 


PAGES 
v 

ix 

1-52 


53-71 


73-102 


Yin  CONTENTS 

PAGES 

mine,  Atlantic,  Mich.,  92.  Barnum  mine,  Ishpeming,  Mich., 
93.  Section  16  mine,  Ishpeming,  Mich.,  94.  Soft  Ore  Hema- 
tite mine,  Ishpeming,  Mich.,  96.  Queen  mine,  Negaunee, 
Mich.,  99. 

MINE  TIMBERING  IN  SECTION  16  OF  THE  LAKE  SUPERIOR  MINING 

-  COMPANY,  MICHIGAN,  BY  C.  ST.  G.  CAMPBELL      .....      103-120 

Shaft  timbering,  108.  Drift  sets,  110.  Square  sets,  112. 
Stulls,  112.  Timber  pillars,  or  cribs,  114.  Docks,  115.  Chutes, 
117.  Staging,  118.  Ladders  and  sollars,  119.  Miscellaneous, 
119. 

THE  FRAMING  OF  RECTANGULAR  SHAFT  SETS,  BY  WILBUR  E.  SAN- 
DERS         123-130 

SQUARE-SET  PRACTICE  AT  BINGHAM,  UTAH,  BY  Louis  S.  GATES      .     131-139 

SQUARE-SET  TIMBERING  AT  BINGHAM,  UTAH,  BY  CLAUDE  T.  RICE     140-143 

Mining  methods,  140.  The  square-set  system,  141.  Pecul- 
iarities of  the  Bingham  practice,  142.  Criticism  of  the  system, 
143. 

MINE  TIMBERING  AT  LAKE  SUPERIOR,  BY  W.  R.  CRANE        .      .      .     144-149 

Timbering  in  shafts,  145.  Concrete  lining,  147.  Timber- 
ing in  drifts  and  stopes,  147. 

TIMBER    AND    TIMBERING    IN    THE    C<EUR   D'ALENE,   BY   J.   H. 

BATCHELLER 150-169 

TIMBERING  AT  THE  CHILLAGOE   MINES,   QUEENSLAND,   BY  T.   J. 

GREENWAY 170-174 

TIMBERING  IN  TASMANIA,  BY  MARK  IRELAND 175-176 

INDEX 177-179 


LIST    OF    ILLUSTRATIONS 


FIGURES  PAGES 

1-5.     Weight  pressure  on  timbers 5-6 

6.  Three-piece  level  set .  8 

7.  Four-piece  level  set 8 

8-10.     Three-compartment  shaft  set 9-11 

11.     Details  of  the  four-piece  set       .            11 

12-13.  Station  for  inclined  shaft      ...      .      .      .__      .      .         12-13 

14-16.     Straight-edge  and  plumb  line 14 

17-20.     Ladders  and  hanging  bolts         15 

21-21  A.     Cribbed  shaft  timbering  with  poles 16 

22-22  A.     Cribbed  shaft  timbering  with  planks 16 

23.  Cribbed  shaft  timbering  with  framed  set 17 

24-25.     Halved  framing  for  shaft  sets 19 

26.  Timbering  of  a  one-compartment  shaft.     Details     .  21 

27.  Timbering  of  a  one-compartment  shaft.     Perspective     .  22 

28.  Method  of  supporting  shaft  sets       .....'..  23 

29.  Lining  for  shafts  in  loose  ground 26 

30.  Spiling  in  running  ground 28 

31.  Framing  of  three-compartment  shaft.     Perspective.      .  29 

32.  Framing  of  single-width  four-compartment  shaft       .      .  31 

33.  Framing  of  double-width  four-compartment  shaft.   Plan 

and  details 32 

34.  Framing    of    double-width     four-compartment     shaft. 

Perspective 33 

35.  Single-piece  set 36 

36.  Two-piece  set 37 

37-38.     Three-piece  set      .      .      . 38 

39.  Four-piece  set 39 

40.  Spiling  in  loose  ground 40 

41.  Post  and  head  board 41 

42.  Crib " 41 

43.  Crib  with  waste  filling 42 

44.  Stull 43 

45.  Stull  and  false  stull 44 

46.  Double-stull  method t  44 

47.  Saddle  back  and  arch '  45 

48.  Saddleback           45 

ix 


LIST    OF    ILLUSTRATIONS 


FIGURES  PAGES 

49.  Penning 46 

50.  Angle  of  underlie  of  stulls     .........  47 

51.  Square  sets  in  stoping 48 

52.  Anaconda  method 50 

53.  Eureka  method 51 

54.  Burlingame  method .  51 

55.  Richmond  method 51 

56.  Anaconda  method  of  framing.     Details 52 

57.  Square-set  timbering  at  Rossland,  B.C 58 

58-59.     Working  floors  at  Rossland,  B.C 60-61 

60.  Square-set  timbering  at  Rossland,  B.C.     Details       .      .  66 

61-63.     Square-set  timbering  at  Rossland,  B.C 69 

64-66.     Stull  timbering,  Le  Roi  mine 77 

67.  Mud-sills  and  ties,  Le  Roi  mine 79 

68.  Details  of  square  sets,  Le  Roi  mine 80 

69.  Square  sets  in  position,  Le  Roi  mine 81 

70-72.     Views  of  chute,  Le  Roi  mine 82 

73.     General  scheme  of  stope,  Le  Roi  mine 84 

74-75.  Lagging  arrangement,  Old  Ironsides  mine       ....  87 

76-77.     Chute  arrangement,  Old  Ironsides  mine 88 

78-79.     Method  of  walling  up,  Baltic  mine 90 

80.  Longitudinal  section  of  stope,  Baltic  mine      ....  91 

81.  Stull  timbering,  Atlantic  mine 92 

82.  Stopes  and  pillars            ,      .            94 

83.  Filling  system,  Section  16  mine 95 

84.  Caving  system,  Soft  Ore  Hematite  mine 97 

85-86.     Stopes  and  pillars,  Queen  mine 100 

87.  Section  16  Mine.     Projection  of  2d  and  10th  levels  .      .  106 

88.  Horizontal  section  through  shaft,  Section  16  mine     .      .  109 

89.  Side  elevation  of  drift  set,  Section  16  mine    ....  110 

90.  End  view  of  drift  set,  Section  16  mine Ill 

91.  Raker,  Section  16  mine 112 

92-93.     Stulls,  Section  16  mine 113 

94.  Method  of  setting  up  machines 114 

95.  Docks 116 

96.  Mills 117 

97.  A  typical  mill  chute 118 

98.  Frame  of  rectangular  shaft  set,  assembled      ....  124 

99.  Laying  out  and  framing  rectangular  shaft  set       ...  127 
100-101.     Square-set  timbering  at  Bingham,  Utah 132 

102.  Transverse  section  of  stope 133 

103.  Transverse  section  of  stope 135 

104.  Short  sets 136 

105.  Butt  cap  and  ground  post 138 

106.  Details  of  square-set  timbering .  141 

107.  Shaft  timbering.     Plan  and  section 145 

108.  Level  timbering  and  square  setting 146 


LIST    OF    ILLUSTRATIONS 


XI 


FIGURES  PAGES 

109.  Forms  of  square-set  joints 148 

110-115.  Square-set  timbers     ...      .      .      .    -..  .      .      .      .      151-152 

116-117.  Square-set  stope   ............  153 

118.  Battered  and  straight  tunnel  sets 154 

119.  Tunnel-set  timbers     .      .      .      . 155 

120.  Two-compartment  shaft 156 

121.  Four-compartment  shaft       .      .      .      .     .     ...     .      .  157 

122.  Angle  braces    ...............  158 

123.  Standard  stope  set 159 

124.  Double  drift  sets        160 

125.  Two-compartment  shaft  station      .......  165 

126.  Four-compartment  shaft  set       .      .      .      ...      .      .  166 

127-131.  Details  of  framing .      .      .      .  167 

132-133.  Stull  stope 168 

134-137.  Templates  and  posts        ..........  170 

138.  Caps  or  stretchers 171 

139.  Miter  box -.^     .     ..  172 

140.  Method  of  framing  posts,  caps,  and  stretchers      ...  173 


MINE    TIMBERING 

BY 

WILBUR  E.    SANDERS 


MINE    TIMBERING1 
BY  WILBUR  E.  SANDERS 

IN  this  necessarily  brief  article  the  systems  of  timbering  dealt 
with  are  those  in  use  among  the  mines  of  the  mountainous  regions 
of  western  United  States.  This  qualification,  of  itself,  requires 
no  apology;  for  the  cosmopolitan  character  of  our  miners  —  man- 
agers and  engineers,  superintendents  and  foremen  —  and  their 
shrewd  keenness  in  devising  ways  to  meet  the  problems  presented 
in  underground  workings,  in  selecting  means  peculiarly  adapted 
to  the  end  in  view,  and  in  improving  upon  well-known  methods 
already  in  vogue,  have  placed  the  science  of  supporting  mine 
excavations  by  timbers,  as  developed  by  them,  far  in  advance  of 
that  in  use  among  the  older  and  less  progressive  mining  commu- 
nities. This  monograph  does  not  include  the  methods  used  in 
coal  mining  in  the  East,  or  that  in  use  in  the  copper  and  soft  iron 
ore  deposits  of  Michigan  and  Minnesota ;  nor  does  it  treat  of 
wood  and  iron  cribbing  for  round  shafts,  or  of  iron  supports  now 
used  in  many  European  mines,  nor  of  timbering  and  metal  sup- 
ports used  in  large  tunnels. 

The  mines  operated  under  these  methods  present  every  known 
characteristic  of  lode  formation.  The  veins  and  ore  deposits  lie 
at  all  angles  of  inclination  or  dip;  they  are  of  all  shapes  and  sizes, 
from  the  small  seam  to  immense  masses  hundreds  of  feet  in 
width,  and  of  all  lengths;  while  the  materials  comprising  them 
and  their  country  formations  vary  in  texture  from  rock  of  strength 
sufficient  to  overlie  considerable  excavations  without  extraneous 
support,  to  the  soft  ground  which  requires  not  only  immense 
quantities  of  timber  and  waste  filling  to  carry  the  workings  safely, 
but  an  eternal  vigilance  upon  the  part  of  those  conducting  the 
operations. 

During  preliminary  work  it  is  important  to  explore  and  de- 
velop the  orebodies  in  the  surest  and  least  expensive  ways,  and, 

i  From  The  Mineral  Industry,  1899,  Vol.  8. 
3 


4  MINE  TIMBERLVG 


except  in  the  case  of  prospecting  hidden  or  blind  deposits,  by 
means  of  bore-holes  from  ;he  surface  downward,  metal  mines 
are  tested  and  all  are  exploited  during  their  earlier  stages  by 
shafts  sunk  or  adit-levels  driven  in  and  with  the  ores.  This 
latter  is  an  axiom  in  mining  during  this  period  of  development, 
and  should  be  invariably  followed  where  possible.  When  once 
the  ores  have  been  opened  up  so  that  an  estimate  may  be  made 
as  to  their  extent  and  general  characteristics,  more  expensive 
works  necessary  to  prepare  the  mine  for  the  larger  operations  of 
economic  ore  extraction  may  be  safely  entered  upon.  It  some- 
times happens  that  the  required  information  as  to  orebodies 
beneath  the  surface  of  a  mining  claim  is  sufficiently  answered  in 
and  by  the  workings  of  adjoining  properties  to  make  preliminary 
prospecting  of  the  deposits  unnecessary;  then  systematic  plans 
for  operating  on  a  large  scale  may  be  properly  inaugurated. 

It  is  not  the  province  of  this  article  to  touch  upon  methods 
of  mining  in  use  above  ground,  whether  by  openwork,  hydraulic 
mining,  or  by  other  processes,  but  rather  to  deal  with  the  support 
of  underground  excavations  by  the  use  of  timbers,  and  the  details 
of  mining  therewith  connected.  Nor  is  it  intended  to  explain 
methods  technically  foreign  to  the  subject,  although  such  will  be 
touched  upon  when  used  as  adjuncts  to  systems  of  timbering,  as 
waste  filling,  etc.  In  the  figures  drawn  to  illustrate  the  article, 
sizes  of  timber  most  frequently  used  have  been  arbitrarily  taken 
for  convenience.  The  figures  giving  dimensions  are  working  draw- 
ings showing  the  methods  of  framing,  as  explained,  and  can 
easily  be  applied  to  frames  and  timbers  of  any  desired  dimensions. 

In  developing  and  exploiting  mines  the  miner  should  remember 
that  unnecessarily  large  openings  for  levels,  shafts,  and  other 
similar  workings,  mean  not  alone  the  breaking  down  and  trans- 
porting of  needless  quantities  of  material,  but  also  the  added 
expense  of  keeping  in  repair  larger  passageways  than  are  neces- 
sary, an  item  of  considerable  importance  in  heavy  or  creeping 
ground.  On  the  other  hand,  the  larger  excavations  are  relatively 
the  easier  and  cheaper  to  drive.  The  rule  should  be  that  the  size 
of  workings  must  be  ample  to  carry  out  their  purposes  properly, 
but  not  larger  than  is  necessary  for  economy  in  operation. 

It  often  happens  that  conditions,  local  or  otherwise,  are  such 
that  the  strongest  timbering  fails  to  withstand  the  pressure  to 
which  it  is  subjected,  and  other  means  of  support  must  be  em- 


MINE  TIMBERING 


ployed.  In  exceptional  cases  large  excavations  may  be  supported 
with  little  or  no  timbering,  but  usually  waste  filling  must  be 
extensively  used  as  an  adjunct  to  timbering  if  the  mine  is  to  be 
kept  open.  Swelling  or  "creeping"  ground,  resulting  from  the 
exposure  of  certain  rocks  and  clays  to  the  air,  whereby  they 
expand  with  a  force  no  timbering  can  resist,  demands  prompt 
attention  that  the  timbers  may  be  relieved  from  abnormal  strain. 
This  is  done  by  making  use  of  an  open  lining  of  lagging,  through 
the  interstices  of  which  sufficient  material  may  be  removed  to 
relieve  the  unusual  pressure  upon  the  frames;  a  process  that  is 
continued  as  long  as  the  conditions  demand.  The  above  scheme 
is  employed  at  the  Ontario  mine,  Park  City,  Utah,  and  in  the 
Never  Sweat  mine,  Butte,  Mont.,  where  a  system  of  narrow 
"square  sets/'  with  open  lagging,  placed  outside  of  the  timbers 
of  the  large  three-compartment  working  shafts,  has  been  success- 
fully employed  to  meet  just  such  conditions  in  swelling  ground. 

There  are  certain  established  principles  connected  with  the  use 
and  framing  of  mine  timbers  that  should  be  borne  in  mind.  Pressure 
is  best  resisted  in  line  with  the  grain  of  the  wood  rather  than  across 
the  grain,  which  maybe  made  clear  by  the  folio  wing  explanation: 


FIGS.  1-3.  —  WEIGHT  PRESSURE  ON  TIMBERS. 

Let  Fig.  2  be  a  section  of  timber  supporting  upon  end  and 
side  the  weight  pressures  represented  by  the  arrows  a  and  b;  a 
acting  in  line  with  the  grain  of  the  piece,  b  at  right  angles  to  the 
grain.  As  shown  in  Fig.  1  each  individual  grain  or  fiber  of  which 
the  block  is  composed  resists  the  pressure  a  by  the  strength  of 
the  combined  fibers  of  the  timber,  or  in  other  words  by  the  full 
strength  of  the  timber  itself.  On  the  other  hand,  Fig.  3,  the  pres- 
sure b  acting  across  the  grain  is  resisted  by  the  power  which  binds 


6 


MINE  TIMBERING 


together  the  .bundle  of  fibers  that  make  up  the  piece,  the  weight 
tending  to  crush  them  down  one  against  the  other  until  the  shape 
and  strength  of  the  timber  are  destroyed.  The  writer  has  himself 
seen  in  Cralk's  Colusa  mine,  Meaderville,  Mont.,  24  in.  of  square- 
sawed  yellow  pine  crushed  down  to  a  thickness  of  8  in.  by  the 
weight  pressing  upon  its  side,  at  right  angles  to  the  grain  of  the 
wood,  while  the  supporting  post  still  retained  its  integrity. 

In  framing  timbers  the  sets  should  be  made  with  especial 
reference  to  the  direction  of  the  pressure  thrust. 

In  Fig.  4  let  us  suppose  the  pressure  upon  the  frame  comes 
from  the  direction  of  the  arrow  a,  in  which  instance  it  will  be  seen 

I8 


A 

r 

i                            /. 

y 
/:   B 

i 

-T— 

c 

b        d 


± 


^* 
-> 

±       1       I       I 

«- 

D 

( 

A 

B 

1 

C 

t           t           t           \           t 

jc  jc 

FIGS.  4  AND  5.  —  WEIGHT  PRESSURE  ON  TIMBERS. 

that  the  full  cross-section  of  the  timber  A  is  supported  at  either 
end  by  the  pieces  B  and  D.  This  joint  is  without  doubt  an 
excellent  one  when,  and  only  when,  the  entire  pressure  upon  the 
frame  comes  from  the  direction  a  or  c.  The  frame,  however,  is 
likely  to  be  subjected  also  to  pressures  from  the  directions  b  and 
d,  to  resist  which  the  timbers  B  and  D  offer  only  a  portion  of  their 
cross-sections  while  the  remaining  parts  x  y  of  the  pieces  tend  to 
split  off  from  the  larger  portions,  thereby  weakening  the  timbers 
by  an  amount  equal  to  the  sections  x'  y'  so  removed.  A  similar 
result  from  the  pressure  c  might  now  cause  the  portion  x  z  to 
split  off  from  C,  in  which  event,  there  remaining,  as  against  the 
pressure  6,  no  shoulder  upon  C  to  support  B  in  place,  the  timber 
B  would  be  forced  from  its  position,  causing  the  frame  to  collapse. 


MINE  TIMBERING  7 

Therefore,  for  resisting  pressure  from  two  or  more  directions  the 
framing  shown  in  Fig.  4  is  not  applicable. 

The  only  satisfactory  remedy  for  this  inherent  weakness  of 
square-shoulder  framing  is  to  make  use  of  the  mitered  joint 
or  beveled  hitch,  as  shown  in  Fig.  5.  In  this  method,  because  of 
the  support  afforded  a  timber  by  the  miter  of  this  joint,  the  pres- 
sure from  any  of  the  directions  a,  6,  c,  and  d  is  resisted  by  the 
strength  of  the  full  cross-section  of  the  piece  against  which  the 
force  acts.  However,  as  shown  in  the  piece  C,  the  simple  miter 
is  not  in  itself  sufficient  to  sustain  any  considerable  thrust  without 
a  tendency  to  wedge  apart  the  timbers  B  and  D,  and  thus  destroy 
the  set.  Without  doubt  the  simplest  and  strongest  joint  obtain- 
able is  some  combination  of  the  square-shouldered  tenon  with 
the  miter  or  beveled  hitch.  This  combination  is  shown  in  the 
joints  supporting  the  piece  A.  Here  the  full  strength  of  the  timber 
is  obtained,  with  no  tendency  to  split  or  slip,  and  weight  up  to 
near  the  point  of  crushing  only  serves  to  bind  the  set  more  firmly 
together. 

Heavy  ground  is  supported  by  the  heavier  timbers;  by  sets 
placed  near  together;  and  by  sets  strengthened  by  reinforcing 
sets  of  timbers. 

Round  timbers  are  stronger  than  square-sawed  pieces,  in 
which  the  grain  of  the  wood  has  been  cut  and  weakened  by  the 
saw.  Used  in  the  mine,  round  timbers  are  less  easy  to  handle 
than  are  the  squared;  they  are  less  easy  to  aline  properly,  and  it 
is  impossible  to  reinforce  satisfactorily  sets  framed  from  such 
timbers  by  the  usual  false  sets  or  pieces.  The  bark  should  in- 
variably be  removed  from  round  timbers,  as  it  collects  moisture 
and  fungus,  and  thus  hastens  the  decay  of  the  wood.  It  also 
prevents  the  pieces  from  becoming  properly  seasoned  before  they 
enter  the  mine. 

TIMBERING  OF  SHAFTS,  STATIONS,  AND  LEVELS 

SHAFTS.  —  Shafts  are  of  two  kinds,  vertical  and  inclined. 
The  former  is  more  frequently  used  in  large  operations,  where 
speed  and  convenience  in  hoisting  are  the  prime  necessity  —  par- 
ticularly in  connection  with  the  more  steeply  inclined  deposits, 
and  with  flat  ones  and  pockets  lying  entirely  beneath  the  sur- 
face. 


MINE  TIMBERING 


1 


1 


L^_._^ ^ 


.1 


FIG.  6.  —  THREE-PIECE  LEVEL  SET. 


-- 

—  ' 

LZ] 





1 

~f" 

J 

J 

J 

I 

1 

—  *'*  • 

. 

= 

If 

i 

-t-f 

^ 

J  — 

^  

_/o!  , 

4- 

—  — 
^— 

i 

L* 

]  [ 

It 

>•' 

rJJ.^ 

; 

1 

FIG.  7.  —  FOUR-PIECE  LEVEL  SET. 


MINE  TIMBERING 


10 


MINE  TIMBERING 


The  usual  size  for  single-compartment  shafts,  and  for  the  hoisting 
compartments  of  the  larger  shafts  in  metal  mining,  is  from  4  to 
6  ft.  in  the  clear  of  the  timbers;  the  com- 
partment used  to  carry  water-columns, 
air-  and  steam-pipes,  and  ladders,  is 
frequently  made  larger  in  cross-section 
than  the  working  compartments.  The 
expense  of  sinking  shafts  and  of  keeping 
them  in  repair  in  average  ground  in- 
creases rapidly  beyond  a  certain  size; 
it  is  therefore  considered  good  practice 
to  make  the  shafts  as  small  as  possible, 
keeping  in  view  the  work  to  be  carried 
on  through  them. 

Inclined  Shafts.  —  Inclined  shafts  are 
used  largely  during  the  preliminary  stages 
of  development  in  veins,  and  other  outr 
cropping  deposits  that  dip  below  the 
horizontal  at  angles  too  small  to  allow 
of  the  economical  use  of  vertical  shafts. 
Similar  methods  of  timbering  both  classes 
of  shafts  are  in  use,  although  at  times 
the  timbering  of  inclined  shafts  ap- 
proaches more  nearly  to  that  employed 
in  supporting  the  level  workings;  as 
when  application  is  made  of  the  three- 
piece  and  four-piece  level  sets  to  in- 
clines (Figs.  6  and  7).  The  single  stull 
piece,  with  head  board,  is  often  used  in 
the  mountains  when  the  hanging  wall  or 
top  rock  is  of  such  strength  as  to  require 
little  support. 

When  the  three-piece  level  set  is  em- 
ployed the  cap  is  usually  lengthened, 
and  the  top  of  each  post  fits  into  gains 
cut  near  the  ends  of  the  cap.  Where  a 
sill  piece  is  desirable  the  sill  is  framed  in 
the  same  manner  as  the  cap,  and  the 
posts  act  as  dividers. 


1 


FIG.  9.  —  THREE-COMPART- 


(See  Fig.  7.)     In 


MENT  SHAFT  SET.          such  use  technically  the  posts  become  end 


MINE  TIMBERING 


11 


plates,  the  cap  and  sill  side  plates,  while  posts  when  used  are 
placed  lengthwise  of  the  shaft  as  distance  pieces  to  separate 
the  sets.  (See  Fig.  8.) 

A  two-compartment  shaft  is  constructed  by  placing  a  third 
post  or  girt  in  position  at  or  near  the  center  of  the  set  in  much 
the  same  manner  as  are  located  the  end  posts  or  plates. 


jH*-8^* 


%-8-*r^- 


-5-1- 


+&4A 


r 


i 


FIG.  10.  —  THREE-COMPARTMENT  SHAFT  SET. 


a  b 


r 


4h 


Tr-iT 


8 

FIG.  11.  —  DETAILS  OF  THE  FOUR-PIECE  SET. 

The  three-compartment  shaft  is  similarly  constructed  by 
locating  two  such  girts  at  their  proper  position,  the  tenons  of  the 
girts  being  V-shaped.  (See  Figs.  8,  9,  and  10.)  Behind  or  back 
of  the  side  plates,  and  in  line  with  the  end  plates  and  girts,  the 


12 


MINE  TIMBERING 


set  is  tightly  blocked  and  wedged  in  place.  Pole  or  plank  lagging 
is  used  where  it  is  necessary  to  prevent  falls  of  loose  rock  from 
the  walls  and  sides  of  the  shaft.  Skip-ways  are  carried  by  the 
sill  piece  or  bottom  side  plate.  Guides  also  are  attached  to 
the  end  plates  and  center  girts  when  safety  devices  are  used  upon 
the  ore-skips. 


FIG.  12.  —  STATION  FOR  INCLINED  SHAFT. 

Other  methods  of  framing  the  four-piece  set,  as  applied  to 
the  inclined  shaft,  differ  from  the  above  framing  in  minor  details, 
and  at  the  same  time  allow  of  the  use  of  the  full  width  of  the 


MINE  TIMBERING 


13 


shaft.  (See  Fig.  11.)  The  halved  system  of  framing,  as  explained 
under  vertical  shafts,  is  rarely  used  for  the  inclines,  and  then  only 
when  posts  are  employed  to  form  the  complete  square  shaft  set. 


FIG.  13.  —  STATION  FOR  INCLINED  SHAFT. 

Stations  for  Inclines.  —  The  stations  constructed  for  inclined 
shafts  are  of  two  kinds,  one  being  so  arranged  that  the  ore  cars 
dump  directly  into  the  hoisting  skip,  held  in  position  just  beneath 
(Fig.  12),  while  in  the  other  a  25-  to  75-ton  ore  bin  is  placed 


14 


MINE  TIMBERING 


beneath  the  station  and  above  the  shaft,  from  which  bin  the  ore 
is  drawn  into  the  skip  for  hoisting  to  the  surface  at  intervals. 
This  station,  while  requiring  more  excavating  to  construct,  is  by 
far  the  most  economical  in  the  end,  as  the  skip  can  be  run  entirely 
independently  of  the  trammers  or  carmen.  (See  Fig.  13.) 


FIG.  14.  —  STRAIGHT-EDGE  AND  PLUMB-LINE. 


1 1'< 

a 


FIGS.  15  AND  16.  —  STRAIGHT-EDGE  AND  PLUMB-LINE. 

Alinement  of  Incline  Sets.  —  Probably  the  simplest  method  of 
alining  the  side  plates  of  inclined-shaft  sets,  in  order  to  get  them 
in  line  one  with  another,  is  by  the  use  of  the  combined  straight- 
edge and  plumb-bob. 


MINE  TIMBERING 


15 


A  straight-edge  is  made  of  a  length  greater  by  a  foot  or  so 
than  the  distance  between  two  sets.  From  the  side  opposite  the 
true  edge  is  built  up  a  frame,  one  piece  of  which  is  so  set  that  a 
plumb-line  attached  at  its  upper  end  will  hang  vertically  along  a 
fixed  line,  marked  upon  it,  when  the  straight-edge  coincides  with 
the  true  inclination  of  the  shaft,  and  at  the  same  time  simulta- 
neously rests  upon  three  bottom  plates.  To  prevent  the  plumb- 
line  from  swinging  too  freely  it  is  confined  at  its  lower  end  within 
comparatively  small  limits  by  a  cleat  attached  to  the  upright 
piece.  (See  Fig.  14.)  The  straight-edge  alone  is  used  to  locate 


Hanging  £  !" 
Bolts 


Edge 


J     L 


___M"_._ 

-«-U-~  J 

H                 i 

11 

:r 

J* 

1 

J 

— 

If 

"f 

I 

4 

J 

f 

• 

4 

, -is-  -- 


16--*! 


JT 

j! 

s 

li 

)>  -S 

1 

i 

f-i. 

ii     A 


FIGS.  17-20.  —  LADDERS  AND  HANGING  BOLTS. 


the  end  plates  evenly  in  line  with  each  other.  (Fig.  15.)  When 
the  sets  are  placed  they  are  bound  in  position  by  hanging  hooks 
or  bolts  (Fig.  20),  as  explained  under  vertical  shafts,  and  when 
so  held  are  blocked  and  wedged  firmly  in  place;  the  straight-edge, 


16 


MINE  TIMBERING 


as  above  described,  being  employed  to  locate  the  sets  in  their 
true  position  during  this  operation. 

Vertical  Shafts.  —  The  timbering  of  shafts  varies  according  to 
the  nature  of  the  ground  and  the  size  of  the  shaft.  Shafts  sunk 
in  some  localities  require  little  if  any  timbering,  while  in  other 
places  they  are  supported  only  by  huge  timbers  that  have  been 
framed  with  the  utmost  precision. 


FIGS.  21  AND  21A.  —  CRIBBED 
SHAFT  TIMBERING  WITH  POLES. 


FIGS.  22  AND  22A.  —  CRIBBED 
SHAFT  TIMBERING  WITH 
PLANKS. 


Cribbed  Shaft  Timbering.  —  In  small  shafts  usually  some 
form  of  cribbing  is  used.  This  system  of  shaft  timbering  is 
the  simplest  and  often  the  cheapest  in  use,  but  it  becomes 
cumbersome  and  expensive  in  large  shafts.  As  usually  employed 
it  requires  little  framing,  is  easy  to  place,  to  repair  or  renew, 
and  to  keep  properly  alined,  and  its  use  enables  the  timber- 
ing to  be  kept  even  with  the  bottom  of  the  shaft  in  sinking, 
if  that  be  necessary. 


MINE  TIMBERING 


17 


The  simplest  form  of  cribbing  is  that  of  poles,  cut  to 
required  lengths  and  placed  in  pairs  across  each  other,  either 
from  above  or  below.  Located  in  this  manner  it  forms  an 
openwork  lining  to  the  shaft.  Strips  aa  nailed  to  the  poles 
upon  the  inside  corners  keep  the  cribbing  in  position.  (See 
Figs.  21  and  21A.) 


FIG.  23.  —  CRIBBED  SHAFT  TIMBERING  WITH  FRAMED  SET. 

Cribbing  is  also  formed  from  sawed  timbers  of  various 
dimensions,  the  most  simple  method  being  that  in  which  planks 
of  the  required  lengths  are  placed  around  the  shaft,  upon 
edge,  and  resting  upon  similar  sets  below  or  supporting  similar 


18  MINE  TIMBERING 

sets  above.  These  sets  are  made  to  resist  the  outside  pressure, 
usually,  by  so  placing  the  two  shorter  or  end  pieces  that  they 
will  hold  apart  the  two  longer  side  pieces,  the  former  in  their  turn 
being  held  in  their  position  by  corner  strips  b  within,  and  nailed 
up  and  down  the  shaft  to  the  side  pieces.  (See  Figs.  22  and  22 A.) 

While  the  method  of  timbering  is  extremely  simple  it  is  un- 
satisfactory, and  good  mining  practice  makes  use  of  the  framed 
set  as  being  stronger  and  in  every  way  better.  The  basis  of  this 
system  is  some  form  of  the  tenon  and  mortise,  whereby  the  ends 
of  the  two  timbers  forming  a  joint  are  framed  with  both  a  tenon 
and  what  might  be  called  an  open  mortise,  the  mortise  of  one 
piece  engaging  the  tenon  of  the  other  and  vice  versa,  to  the  end 
that  each  piece  supports  or  keys  its  mate  in  place.  See  Fig. 
23,  a,  b,  and  c,  which  show  the  more  simple  forms  of  this  method 
of  cribbing,  the  latter  c  being  excellent  for  the  reason  that  it 
causes  the  edges  of  the  planks  on  the  sides  to  break  joint  with 
the  edges  of  the  end  planks  in  a  way  to  stiffen  the  shaft  and 
prevent  the  sets  from  moving  horizontally  one  upon  another. 
The  methods  of  framing  planks  for  these  styles  of  cribbing  are 
shown  in  Fig.  23,  d  and  e. 

Halved  Framing  for  Shaft  Sets.  —  A  development  of  the  tenon 
and  mortise  framing  of  joints  is  of  almost  universal  application 
in  advanced  methods  of  supporting  vertical  shafts.  This  method 
is  'applied  to  the  cribbed  system  as  shown  in  Fig.  24,  a,  A,  b, 
and  B.  The  method  of  framing  the  pieces  for  openwork  cribbing 
is  shown  in  Fig.  24,  a,  and  for  tight  cribbing,  Fig.  24,  b. 

Fig.  24  B  also  shows  the  framing  of  the  opening  from  the 
shaft  to  the  levels.  False  timbers  or  struts  are  used  temporarily 
to  hold  the  sides  of  the  shaft  intact  while  this  opening  is  being 
framed  into  the  level,  or  the  framing  can  be  placed  before  the 
planks  are  removed  from  the  cribbing.  A  stronger  and  more 
satisfactory  frame,  however,  is  obtained  by  the  combined  beveled 
hitch  and  halved  joint.  The  most  satisfactory  use  of  this  com- 
bination is  that  in  which  the  top  and  bottom  of  the  side  plates 
are  made  to  break  joint  with  top  and  bottom  of  the  end  plates. 
(See  Fig.  25.)  Details  of  this  framing  are  given  in  Fig.  25,  a  and  6, 
while  the  method  of  placing  the  timbers  is  shown  in  the  isometric 
perspectives  A  and  B. 

Compartments  are  formed  by  cutting  the  side  plates  to  receive 
a  center  girt  that  is  framed  very  similarly  to  the  end  plates. 


MINE  TIMBERING 


19 


T^Tl 


y=r 


,5-1 0A " — . 


£*£ * * 

.«  "       p 

*4^ — 4ilo^ ; J/i 


Z5S 


FIGS.  24  AND  25.  —  HALVED  FRAMING  FOR  SHAFT  SETS. 


20  MINE  TIMBERING 

The  tight  cribbing  has  been  used  for  large  shafts  in  heavy 
ground.  On  the  Comstock  lode,  Virginia  City,  Nev.,  several  of 
the  important  shafts  were  timbered  with  a  solid  cribbing  of 
14-in.  pieces. 

Square-Set  Shaft  Timbers.  —  In  the  square-set  system,  as 
applied  to  the  timbering  of  vertical  shafts,  the  heavier  timbers 
of  a  cross-section  of  6  in.  and  upward  are  employed.  A  set 
consists  of  the  side  and  end  pieces,  with  posts  used  to  separate 
the  horizontal  frames.  In  the  larger  shafts  divisional  timbers, 
called  girts,  are  used  to  separate  the  compartments.  The  side 
and  end  pieces  are  called  wall  plates,  for  the  reason  that  they 
frame  the  sides  or  walls  of  the  shaft.  The  longer  pair  of  plates 
are  designated  as  side  wall  plates  —  usually  called  side  plates  — 
and  the  shorter  pair  as  end  wall  plates,  or  end  plates.  Shafts  of 
a  single  compartment  are  characterized  as  one-compartment 
shafts ;  and  those  which  are  divided  by  inner  struts  or  girts  into 
two,  three,  and  four  divisions,  as  two-,  three-,  and  four-compart- 
ment shafts.  It  is  doubtful  if  shafts  larger  than  with  four 
compartments  can  be  successfully  operated  in  deep  mining,  unless 
in  exceptional  cases.  The  framing  of  the  various  sized  shafts  is 
very  similar,  differing  only  in  details  that  will  be  explained  later. 

One-Compartment  Shafts.  —  The  timbering  of  a  one-com- 
partment shaft  consists  of  two  side  plates,  a,  two  end  plates,  b, 
and  four  posts,  c,  which  technically  make  a  single  set,  successive 
sets  being  used  to  the  bottom  of  the  shaft  to  support  the  sides, 
and  a  lining  of  plank  or  lagging,  d,  is  employed  to  prevent  falls 
of  loose  material  into  the  opening.  (See  Fig.  26.)  For  the 
wall  plates  the  halved  method  of  joint  framing  is  employed,  and 
at  the  same  time  a  hitch  or  square  shoulder  one  inch  deep  is  cut 
in  the  tenon  as  a  support  for  the  post.  This  halving  of  the  tim- 
bers, if  used  alone,  greatly  weakens  them,  and  the  beveled  hitch 
is  framed  from  their  inner  faces  so  that  their  full  strength  may 
be  brought  to  the  support  of  the  shafts.  (Fig.  26,  z.)  The 
dimensions  of  the  set  are  such  that  the  plates  when  fixed  in  posi- 
tion are  separated  5  ft.  from  center  to  center,  the  practice  being 
to  increase  the  size  of  the  timbers  in  heavy  ground  rather  than  to 
place  the  frames  nearer  together. 

In  framing  the  sets  the  utmost  care  is  taken  that  the  meas- 
urements shall  be  exact,  and  that  the  timbers  shall  be  cut  true 
to  the  line,  especially  for  all  important  working  shafts,  large  and 


MINE  TIMBERING 


21 


small.     A  center  line  is  laid  off  upon  the  inside  faces  of  the  plates 
and  the  measurements  for  tenons,  mortises  and  miters  are  taken 


d. 


Two  of  this          a 


Top  View 


Front  View 


Bottom  View 


Back 


View 


Two  of  this        b 


"A"" 
"b» 

Top 

View 

I 

Front  View 


Bottom  View 


Back 


View 


ia 


Two  of  this       c 


1 


FIG.  26.  —  TIMBERING  OF  A  ONE-COMPARTMENT  SHAFT.     Details. 


MINE  TIMBERING 

from  this  line.  The  faces  of  the 
tenons  and  shoulders  are  made  at 
right  angles  to,  or  parallel  with, 
and  measured  from  the  face  of  the 
plate.  These  precautions  are  neces- 
sary because  of  variations  in  the 
dimensions  of  timbers.  The  halved 
tenons  of  each  side  plate  occupy 
the  lower  portion  of  that  timber, 
those  of  the  end  plates  the  upper 
part,  so  that  when  in  place  the  side 
plates  support  the  end  plates  by 
their  tenons.  See  Fig.  27,  a,  show- 
ing the  isometric  perspective  of  this 
shaft. 

Locating  Shaft  Sets.  -  -  When  a 
shaft  is  to  be  sunk  from  a  sur- 
face too  level  to  furnish  possi- 
bilities for  the  disposal  of  the  waste 
material  coming  up  from  below,  it 
is  necessary  to  elevate  the  top  or 
collar  of  the  shaft  above  the 
surface  of  the  ground.  This  is 
accomplished  by  building  up  a 
cribwork  of  rough  timbers  to  the 
desired  hight  by  placing  logs  of 
sufficient  length  in  layers  by  fours 
or  more  across  each  other,  with  the 
shaft  opening  in  the  center.  This 
cribbing  is  reinforced  by  waste  filled 
in  against  it,  and  with  this  as  a 
backing  the  shaft  sets  are  located 
in  position  and  blocked  securely 
against  the  cribbing. 

It  also  happens  at  times  that  the 
top  material  in  which  a  shaft  is  to 
be  sunk  is  too  loose  to  support  the 
sets  by  simple  blocking.  In  this  case 

the  tenons  at  both  ends  of  the  side 
FIG  27.  —  TIMBERING  OF  A  ONE-  ,   ,  , 

COMPARTMENT  SHAFT.  Perspective,    plates  are  made  to  extend  beyond 


MINE  TIMBERING 


23 


the  limits  of  the  shaft,  and  these  extensions  are  bolted  to  cross 
timbers  above  or  rest  upon  such  timbers  as  a  support,  the  latter 
being  of  a  length  sufficient  to  bear  upon  the  ground  to  either 
side  of  the  shaft,  and  thus  support  its  weight  until  it  shall 
have  entered  rock  firm  enough  to  afford  secure  support  to 
the  sets  by  blocking  and  wedging  in  the  usual  manner.  (See  Fig. 
28,  a  and  &.) 


a-PIan 


T>Elevation       &. 


FIG.  28.  —  METHOD  OF  SUPPORTING  SHAFT  SETS. 

The  process  by  which  shaft  sets  are  located  and  fixed  in  posi- 
tion as  integral  parts  of  the  shaft  is  as  follows :  The  side  plates  of 
the  set  to  be  put  in  place  are  swung  to  the  set  above  by  hanging 
hooks  or  bolts,  which  are  made  usually  of  0.875-in.  round  iron, 
hooked  at  one  end  and  threaded  at  the  other  as  far  as  may  be 
necessary.  (See  Fig.  20.)  These  hooks  are  used  in  pairs,  the 
length  of  each  being  about  4  in.  greater  than  one-half  the  hight 


24  MINE  TIMBERING 

of  each  set  from  outside  to  outside  of  the  wall  plates,  measured 
vertically.  Thus,  with  plates  of  12-in.  cross-section  in  a  5-ft. 
set,  the  length  of  each  hook  would  be  about  3  ft.  4  in.,  with  the 
bolt  end  threaded  for  6  to  8  in.  These  bolts  are  the  simplest 
and  most  easily  manipulated  device  yet  constructed  for  hanging 
a  set  in  place.  Holes  are  bored  through  each  side  plate,  two 
at  fixed  points  near  either  end,  to  receive  the  bolts,  one  hole  at 
each  end  being  used  to  hang  the  plates  to  the  set  above  while  the 
other  holes  are  intended  for  the  next  succeeding  set.  Cast-iron 
washers  are  used  between  the  plate  and  nut  to  give  bearing  to 
the  latter  when  binding  the  sets  together.  The  bolts  having  been 
located  in  the  plates,  the  hooks  attached  to  the  loose  timbers 
are  caught  upon  the  hooks  of  the  set  above,  the  end  plates  are 
put  into  place,  their  tenons  resting  upon  the  tenons  of  the  side 
plates,  the  posts  are  set  in  the  hitches  cut  to  receive  them,  and 
the  nuts  are  screwed  down  until  the  frame  is  tightly  bound  to  the 
set  above.  If  this  upper  set  is  properly  level,  and  the  framing 
of  all  the  parts  correctly  done,  the  center  line  marked  upon  the 
new  set  must  be  level.  Blocks  x  are  placed  on  the  two  sides  of 
each  corner  in  line  with  each  plate,  between  wall-rock  and  frame, 
and  wedges  are  driven  to  tighten  the  set  in  its  proper  position. 
(See  Figs.  26  and  27.)  The  back  of  each  plate  carries  a  strip 
nailed  thereto,  and  resting  upon  this  as  a  ledge  for  support  is 
placed  the  plank  lagging  or  lining  of  the  set.  Filling  is  stowed 
behind  the  lagging,  as  the  planks  are  put  in  position,  sufficient  to 
prevent  movement  of  the  surrounding  ground  that  would  be 
likely  to  throw  the  shaft  out  of  plumb.  The  same  process  is 
repeated  as  the  sinking  progresses  to  the  bottom  or  sump  of  the 
shaft.  In  dangerous  ground  the  practice  is  not  to  remove  the 
bolts  after  the  sets  have  been  located,  and  it  is  well  in  any  case 
to  leave  them  in  place  for  several  sets  from  the  bottom  of  the 
shaft,  in  order  to  bind  the  frames  firmly  together  at  this  point. 

Alinement  of  Vertical  Shafts.  —  Various  methods  of  alining 
the  timbers  of  vertical  shafts  are  in  use,  the  most  satisfactory 
probably  being  the  combination  straight-edge  and  plumb-bob. 
A  double  straight-edge  of  a  length  sufficient  to  extend  over  three 
wall  plates  in  position  —  about  11  ft.  for  5-ft.  sets  —  is  made, 
near  the  center  of  which  is  attached  a  plumb-line  of  a  length  of 
about  4  ft.  A  hole  is  cut  in  the  straight-edge  near  its  bottom 
end,  in  which  the  bob  may  swing  freely,  while  a  cleat  attached 


MINE  TIMBERING  25 

just  above  this  point  serves  to  confine  the  line  so  that  it  is  quickly 
located  at  the  center  mark,  and  a  line  is  drawn  upon  the  flat 
side  of  the  piece  parallel  to  the  true  edge,  with  which  mark  the 
plumb-line  must  coincide  when  the  true  edge  is  exactly  vertical. 
(See  Fig.  16.) 

The  set,  having  been  bound  to  the  one  above,  and  blocked 
to  its  approximate  position,  is  then  alined  truly  with  the  two 
sets  above  by  means  of  the  straight-edge  (Fig.  15)  and  by  the 
combined  straight-edge  and  plumb-line  (Fig.  16),  and  is  brought 
to  its  exact  position  vertically,  the  wedges  being  driven  first  at 
one  side  and  then  the  other  until  the  set  is  in  place.  Usually 
the  sets  are  alined  first  at  the  side,  the  side  plates  first  at  one 
end  and  then  at  the  other  being  brought  into  position  by  the 
wedges,  when  the  process  is  repeated  with  the  end  plates  in 
order  to  aline  the  ends  of  the  shaft.  Should  it  be  a  shaft  of  two 
or  more  compartments  the  side  plates  are  alined  by  blocks  and 
wedges  in  line  with  the  divisional  girts  separating  the  compart- 
ments after  the  corners  of  the  shaft  have  been  brought  to  their 
places  in  the  same  manner  as  has  been  described.  If  the  timbers 
are  rightly  framed  the  inner  faces  of  the  wall  plates  should  exactly 
coincide  vertically  with  the  inner  faces  of  the  sets  above.  The 
frame  having  thus  been  brought  into  and  fixed  in  its  true  position, 
the  lining  is  placed  and  the  set  is  complete.  (See  Fig.  27.) 

Repairing  Shafts.  —  When,  by  reason  of  undue  strain,  weak- 
ness develops  in  one  or  more  of  the  timbers  of  a  shaft,  the  faulty 
pieces  must  be  removed  and  replaced  by  new  ones.  Preliminary 
to  this  work  several  sets,  particularly  those  next  above  the  point 
at  fault,  are  tightly  bound  together  by  the  hanging  bolts.  If 
posts  only  are  to  be  replaced  it  may  be  accomplished  by  removing 
the  lagging  adjacent,  excavating  enough  ground  from  behind  each 
post  to  allow  of  its  being  driven  back  from  the  shaft  until  it  is 
clear  of  the  timbers,  or  it  may  be  chopped  out  with  little  trouble. 
The  new  post  is  then  placed  in  position  from  behind,  being  driven 
or  wedged  into  place  and  fitting  into  the  hitch  framed  to  receive 
each  post  in  the  plates.  When  necessary  to  replace  the  wall 
plates  the  lagging  of  the  adjoining  sets  above  and  below  is 
removed,  the  blocks  are  knocked  away  and  the  posts  taken  out, 
when  the  plates  may  be  released  and  new  ones  put  in  place. 
The  posts  are  then  returned  to  their  position,  the  set  is  bound 
to  the  plates  above  and  below  by  bolts,  blocked,  wedged,  and 


26 


MINE  TIMBERING 


alined,  lining  is  put  in,  and  the  repairs  are  complete.  It  may 
happen  that  the  ground  will  not  stand  during  this  process,  in 
which  case  false  timbers  and  lining  must  be  used  to  hold  the 
walls  of  the  shaft  in  place. 

Timbering  Shafts  in  Loose  Ground.  —  Shafts  are  frequently 
sunk  in  ground  that  breaks  away  from  the  walls  before  a  set  can 
be  placed  in  position,  and  a  quick  process  of  lining  the  sides  of 
the  excavation  is  necessary.  A  method  of  false  lining,  largely  in 
use  throughout  the  West,  keeps  the  loose  earth  from  falling.  It 
consists  of  planks  of  desired  lengths  placed  vertically,  and  so 
blocked  and  wedged  into  position  as  to  press  each  piece  out- 
wardly against  the  walls.  The  top  end  of  the  plank  is  blocked 
from  the  wall  against  the  lagging  of  the  last  set  placed  in  posi- 
tion, reaching  a  foot  or  so  above  the  wall  plates  of  that  set.  The 
plank  is  further  blocked  and  wedged  away  from  the  wall-plates 
themselves,  the  effect  of  this  being  to  throw  the  foot  of  the  piece 
backward  from  the  shaft  against  the  side  of  the  excavation,  and 
thus  prevent  the  material  from  coming  in.  This  lining  is  often 
carried  completely  around  the  shaft.  (See  Fig.  29.) 


FIG.  29.  —  LINING  FOR  SHAFTS  IN  LOOSE  GROUND. 
Timbering    Shafts    in    Running    Ground.  —  In    soft    running 
ground,  or  loose  ground  too  heavy  to  allow  of  placing  the  false 


MINE  TIMBERING  27 

lining  above  described,  a  method  of  spiling  is  employed  that  is 
practically  identical  with  that  used  for  driving  levels  through 
similar  material.  The  process  consists  of  supporting  the  dan- 
gerous ground  beneath  the  last  set  placed  in  position,  by  what 
might  be  termed  an  enclosing  and  protecting  shield  of  plank 
spiling  or  forepoling,  that  is,  advanced  downward  from  that  set 
piece  by  piece  as  the  material  is  excavated  from  within.  The 
spiling,  a,  sharpened  at  the  foot,  and  often  shod  with  iron  at  the 
head,  is  driven  with  a  sledge,  one  plank  at  a  time  being  advanced 
for  a  short  distance  as  the  material  is  withdrawn  from  before  it. 
The  spiling  is  held  in  position  by  the  set  and  the  material  through 
which  it  is  being  forced,  only  enough  of  this  being  removed  at  a 
time  to  allow  it  to  be  driven  a  short  distance;  otherwise  the 
pressure  from  without  may  force  the  lining  into  the  shaft.  Each 
plank  around  the  shaft  is  driven  successively  one  by  one,  until 
the  entire  shield  has  been  advanced,  when  the  process  is  repeated 
and  continued  until  the  shaft  has  been  excavated  to  a  depth 
sufficient  to  allow  of  the  placing  of  another  set  in  position,  the 
idea  being  to  advance  the  shield  by  successive  small  stages  during 
the  work. 

The  spiling  is  started  at  a  considerable  angle,  but  as  it  is  driven 
downward  it  tends  to  approach  nearer  and  nearer  the  vertical 
until,  when  the  new  set  has  been  permanently  located,  tail  pieces 
or  bridges  b  are  placed  to  hold  the  bottom  of  the  planks  in 
position,  and  at  the  same  time  to  furnish  ait  opening  between 
the  plates  and  the  foot  of  the  shield  through  which  to  drive  the 
spiling  for  the  next  succeeding  set.  These  tail  pieces  may  be 
permanently  left  in  place,  or  removed  in  order  to  allow  the  planks 
to  settle  against  the  top  of  the  spiling  below,  binding  the  latter 
in  place  and  making  a  closer  lining.  Ledge  strips  c  may  be 
attached  to  the  plates,  and  the  usual  close  lining  placed  about 
the  shaft  as  additional  security,  and  to  keep  from  the  shaft  ma- 
terial that  otherwise  might  work  in  at  the  corners.  The  posts 
prevent  spiling  from  being  placed  vertically  so  as  to  form  a 
continuous  close  lining,  which  difficulty  may  in  a  measure  be 
overcome  by  diagonal  spiling  so  placed  as  to  cover  these  openings, 
whether  they  occur  at  the  sides  or  at  the  corners  of  the  com- 
partment shafts.  Where  possible  the  sets  should  be  blocked  and 
wedged  to  place  in  order  that  the  shaft  may  be  kept  plumb,  and 
the  hanging  hooks  should  always  be  retained  in  treacherous 


28 


MINE  TIMBERING 


ground.  The  above  process  is  repeated  successively  until  the 
shaft  has  entered  firm  ground,  when  the  usual  methods  of  tim- 
bering may  be  resorted  to.  (See  Fig.  30.) 


FIG.  30.  —  SPILING  IN  RUNNING  GROUND. 

Two-Compartment  Shafts.  —  In  preliminary  operations,  in  a 
mine  where  pumping  is  necessary,  two-compartment  shafts  are 
employed,  one  of  the  divisions  being  given  up  to  hoisting  and  the 
other  to  pumping  and  ladders.  Both  compartments  are  made 
of  the  same  size,  the  usual  practice  in  the  West  being  for  each 
division  to  be  4  ft.  along  the  length  of  the  shaft  by  4  ft.  6  in. 
across  its  width,  hoisting  cages  being  most  frequently  constructed 
for  operating  in  compartments  of  those  dimensions.  The  tim- 
bering of  a  shaft  of  this  size  is  framed  in  a  manner  almost  iden- 
tical with  that  of  the  one-compartment  shaft,  with  the  exception 
that  the  side  plates  are  made  longer,  and  that  a  divisional  piece, 
called  a  center  girt,  is  made  to  fit  by  tenon  and  mortise  across 
the  center  of  the  side  plates.  Center  posts  are  also  used  to 


MINE  TIMBERING 


29 


strengthen  and  stiffen  the  frame.     The  methods  of  locating  and 
alining  the  sets  are  those  used  for  the  one-compartment  shaft. 
Three-Compartment  Shafts.  —  Should  the  mine  warrant  more 


FIG.  31.  —  FRAMING  OF  THREE-COMPARTMENT  SHAFT.     Perspective. 


30  MINE  TIMBERING 

extensive  hoisting  appliances,  a  third  and  larger  compartment  for 
pumping  is  added  to  the  two-compartment  shaft,  while  the 
smaller  compartments  are  given  up  to  hoisting.  Because  of  the 
jar  and  strain  upon  the  timbers  from  winding,  this  work  should 
be  done  in  the  compartments  that  are  supported  by  the  solid 
side  plate,  as  they  are  more  rigid  and  self-sustained. 

Although  three-compartment  shafts  are  often  enlargements 
from  two-compartment  shafts,  nevertheless  most  of  the  large 
working  shafts  throughout  the  West  are  those  of  three  compart- 
ments that  have  been  commenced  and  carried  to  the  bottom  as 
such.  Fig.  31  gives  the  isometric  perspective  of  a  shaft  of  this 
type.  This  framing  is  such  as  obtains  the  greatest  possible  stiff- 
ness and  strength  for  the  wall  plates,  and  represents  the  most 
advanced  timbering  in  use.  The  arrangement  is  excellent.  The 
small  cage  for  the  use  of  the  pumpmen,  traveling  closely  against 
one  of  the  side  plates  to  allow  space  at  the  opposite  side  of  the 
compartment  for  locating  the  water-column,  air-  and  steam-pipes, 
is  hoisted  by  an  independent  engine,  and  the  safety  arrangement 
for  the  ladders  is  carefully  designed. 

The  sets  are  located  in  the  same  manner  as  are  those  of  the 
single-compartment  shaft.  The  side  plates  are  hung  to  the  plates 
above,  the  end  plates  are  placed  in  position,  the  solid  center  girt 
is  fitted  into  the  mortise  cut  to  receive  it  in  the  center  of  the 
solid  side  plate,  the  divisional  girt  is  located  at  the  joint  between 
the  long  and  short  side  plates,  the  eight  posts  are  placed,  and 
the  set  is  tightly  bound  by  the  hanging  bolts  to  the  set  above, 
blocked,  wedged  and  alined.  The  side  plates  are  sometimes 
made  of  a  single  piece,  framed  to  receive  two  solid  center  girts, 
which  make  the  shaft  more  rigid.  Long  timbers  of  this  kind  are 
difficult  to  handle  in  a  shaft,  and  it  is  not  always  possible  to  use 
them.  Where  possible  they  should  be  placed  at  the  stations, 
both  above  and  below,  in  order  to  make  the  frame  of  the  station 
set  as  strong  as  possible,  as  shown  in  Fig.  31. 

The  principal  reason  for  the  almost  invariable  adoption  of  the 
double-hoisting-compartment  shaft  in  large  operations  through- 
out the  West  is  that  of  balancing  the  loads  in  winding.  One  of 
the  cables  winds  over,  the  other  under,  the  same  engine-shaft, 
and  when  the  two  drums  or  reels  are  both  clutched  to  the  shaft 
the  weight  of  one  cage  and  load  acts  in  a  measure  to  balance 
the  other,  thus  saving  power. 


MINE  TIMBERING 


31 


Four-Compartment  Shafts.  —  Four-compartment  shafts,  with 
three  hoisting  divisions,  may  be  divided  into  three  classes,  viz.: 
the  single-width  shaft,  largely  used  throughout  the  Witwatersrand 
goldfields  of  South  Africa;  the  "L"  shaft,  now  practically  aban- 
doned for  good  reasons;  and  the  double-width  shaft,  which  it 
would  seem  is  likely  to  come  into  general  use  as  being  one  pecul- 
iarly adapted  to  the  vast  operations  of  extensive  mining. 

In  the  single-width  four-compartment  shaft  the  two  end 
hoisting  compartments  are  employed  for  raising  ore,  and,  on 
occasion,  for  lowering  timbers;  the  third  is  used  in  sinking  and 
by  the  pumpmen,  and  likewise  for  lowering  timbers  into  the  mine, 
while  the  fourth  compartment  is  given  up  to  the  pumps,  the 
water-columns,  air-  and  other  pipes,  and  to  the  ladders.  The 
framing  of  the  timbers  for  this  shaft  is  almost  identical  with  that 
for  the  three-compartment  shaft,  except  that  the  divisions  are 
such  that  each  section  of  the  side  plates  supports  two  compart- 
ments. (See  Fig.  32.) 


FIG.  32.  —  FRAMING  OF  SINGLE-WIDTH,  FOUR-COMPARTMENT  SHAFT. 

The  double-width  four-compartment  shaft  practically  com- 
prises two  two-compartment  shafts  placed  side  by  side,  the  end 
plates  being  lengthened  in  order  to  form  a  double-width  shaft. 
Two  of  the  end  compartments  are  used  for  the  hoisting  of  ore 
and  the  lowering  of  men  and  timbers,  one  of  the  two  remaining  is 
employed  as  a  cageway  for  pumpmen  and  timbermen,  with  its 
station  cut  on  the  opposite  side  of  the  shaft  from  that  for  the 
hoisting  divisions,  while  the  other  is  given  up  to  the  uses  of  the 
pump  and  for  carrying  the  water-columns,  air-  and  other  pipes, 
and  ladders.  See  Fig.  33,  giving  the  plan  of  the  shaft,  and  a,  b,  c 
and  d  the  method  of  framing  the  timbers,  which  is  similar  to  that 
for  the  three-compartment  shaft,  and  Fig.  34,  showing  the  iso- 
metric perspective  of  the  construction. 


32 


MINE  TIMBERING 


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FIG.  33.  —  FRAMING  OF  DOUBLE-WIDTH  FOUR-COMPARTMENT  SHAFT. 
Plan  and  details. 


MINE  TIMBERING 


33 


The  wall  plates  of  this  shaft  are  solid  throughout  their  length, 
giving  great  strength  and  rigidity  to  the  frame;  none  of  the  tim- 


FIG.  34.  —  FRAMING  OF  DOUBLE-WIDTH  FOUR-COMPARTMENT  SHAFT. 

Perspective. 


34  MINE  TIMBERING 

bers  are  so  long  as  to  render  their  handling  in  the  shaft  difficult, 
while  at  the  same  time  the  excavation  is  nearly  square  in  cross- 
section,  and  of  a  size  to  facilitate  the  breaking  of  ground,  and 
the  placing  of  the  frames  in  position.  Furthermore,  the  bracing 
received  by  the  plates  from  the  interior  cross  girts,  both  long  and 
short,  greatly  solidifies  and  strengthens  the  set.  The  great  capac- 
ity of  this  shaft,  together  with  its  compactness,  strength,  and 
rigidity,  and  its  accessibility  for  repair,  renders  it  especially 
adapted  to  extensive  mining  operations.  As  compared  with  the 
three-compartment  shaft  this  shaft  requires  the  excavation  of 
but  450  cu.  ft.  more  of  material  in  each  100  ft.  of  its  depth  than 
does  the  former. 

Ladders.  —  The  ladders  that  are  placed  in  the  man-ways  of  a 
shaft,  and  in  other  inclined  and  vertical  passageways  throughout 
a  mine,  are  usually  made  in  5-,  10-  and  15-ft.  lengths  or  there- 
abouts. (See  Figs.  17,  18  and  19.)  They  consist  of  two  sup- 
porting 2x4-in.  scantlings,  placed  parallel  about  14  in.  apart, 
to  which  are  fixed  cross  pieces  or  rungs  at  regular  spaces  of 
about  10  in.  The  rungs  may  be  of  wood  or  iron,  preferably  the 
latter,  unless  the  mine  waters  are  sufficiently  acid  to  attack  the 
iron  —  which  is  often  the  case  in  the  deep  workings.  The  wooden 
rungs  are  often  simply  spiked  to  the  scantlings,  or  they  may  be 
set  into  hitches  cut  in  the  edges  of  the  side  pieces,  and  nailed 
firmly  in  place.  Frequently  the  scantlings  are  bored,  and  turned 
rungs  are  fitted  into  the  holes,  the  ends  of  the  rungs  being  wedged 
to  hold  them  in  place.  While  this  method  makes  an  excellent 
ladder,  the  holes  weaken  the  scantlings  materially,  and,  further- 
more, it  is  almost  impossible  to  replace  a  rung  without  destroying 
the  ladder.  The  most  substantial  ladder,  and  one  easily  repaired, 
is  the  following :  The  inner  face  of  each  scantling  is  bored  at  the 
required  intervals  to  a  depth  of  1  in.  in  order  to  receive  the  ends 
of  16-in.  lengths  of  0.75-  or  0.875-in.  common  iron  pipe,  cut 
exactly.  At  every  fifth  rung  smaller  holes,  concentric  with  the 
others,  are  bored  entirely  through  the  scantlings,  through  which 
and  through  the  lengths  of  pipe  located  at  such  points  are  passed 
20-in.  lengths  of  0.75-  or  0.875-in.  round  iron,  threaded  at  the 
ends  to  receive  nuts.  When  the  different  rungs  of  the  ladder 
have  been  located  in  their  places  these  nuts  are  tightened  upon 
washers  fixed  between  them  and  the  scantlings,  binding  the  ladder 
frame  securely  together.  These  rungs  possess  great  strength, 


MINE  TIMBERING  35 

while  but  little  strength  is  lost  to  the  scantlings,  and  the  ladder  is 
easily  repaired. 

Shaft  Station  Sets.  —  At  various  depths,  usually  at  intervals 
of  100  ft.,  levels  are  run  from  the  shaft,  to  and  through  the  inner 
workings  of  the  mine,  and  at  such  points  stations  or  large  rooms 
are  excavated  in  the  walls  of  the  shaft,  and  timbered  to  serve  as 
centers  for  the  storage  of  material  of  all  kinds,  whether  coming 
from  or  to  be  distributed  to  the  various  working  places.  The 
construction  of  these  stations  necessitates  a  change  from  the 
usual  shaft  framing  at  such  points,  in  order  to  obtain  the  needed 
hight  for  an  entrance  from  the  shaft  to  the  station.  Should  the 
shaft  have  been  carried  below  the  point  for  a  station,  the  obstruct- 
ing wall  plates  at  the  entrance  must  be  removed,  together  with 
their  girts,  and  the  posts  both  above  and  below.  The  longer 
posts,  fitting  into  the  gains  framed  in  the  plates,  are  then  located, 
and  distance  pieces  for  the  walls  and  girts  for  the  center  of  the 
shaft  —  the  same  being  tenoned  to  mortises  in  the  posts  —  are 
placed  in  position,  occupying  that  of  the  wall  plates  removed, 
except  that  the  station  entrance  is  left  free  of  such  pieces.  The 
remaining  sides  of  the  shaft  are  then  lined  with  the  usual  tight 
lagging.  See  the  isometric  perspectives  of  the  three-  and  four- 
compartment  shafts.  (Figs.  31  and  34.)  False  pieces  or  temporary 
struts  holding  in  place  timbers  to  support  the  walls  of  the 
shaft  during  this  operation  are  used  when  necessary. 

STATIONS.  —  The  ordinary  working  station  is  made  of  a  width, 
in  the  clear  of  its  framing,  of  the  two  hoisting  compartments,  or 
of  a  width  which  is  enlarged  at  the  pumping  stations  by  an  addi- 
tional chamber  usually  equal  in  width  to  the  length  of  the  pump 
compartment,  for  the  accommodation  of  the  pump;  the  usual 
practice  being  to  make  the  inner  faces  of  the  station  sets  aline 
with  those  of  the  shaft  timbers. 

In  hight  the  stations  are  made  equal  to  that  of  the  shaft 
entrance,  less  the  thickness  of  the  flooring,  but  the  roof  is  made 
to  slant  downward  from  the  second  or  third  station  set  to  the 
end  of  the  room.  The  length  of  the  station  varies  with  the 
conditions,  from  20  to  40  ft.  being  usual. 

The  timbering  of  stations  consists  of  the  four-piece  level  sets, 
enlarged  and  placed  at  such  distances  apart  as  the  nature  of  the 
ground  requires,  usually  from  5  to  10  ft.  Distance  pieces  or  girts 
are  used  to  hold  the  sets  in  position,  this  in  connection  with  the 


36  MINE  TIMBERING 

usual  blocks  and  wedging.  Ordinary  plank  lagging  prevents  the 
fall  of  loose  rock,  and  a  flooring  of  2-  or  3-in.  planking  is  laid,  to 
which  is  screwed  a  turning  sheet  of  boiler  plate,  whereon  ore  cars 
may  be  turned  or  slewed  around.  A  sump  tank  to  hold  the 
mine  water  that  is  to  be  pumped  to  the  surface  is  framed  and 
placed  beneath  the  pump  division  of  the  station. 

In  loose  ground  it  is  necessary  to  timber  the  station  by  a 
system  of  loose  spiling,  analogous  to  the  method  explained  in 
driving  levels  through  similar  material. 

LEVELS.  —  Levels  include  all  those  approximately  horizontal 
workings  through  which  mine  transportation  to  and  from  the 
working  places  is  carried  on,  and  include  adits,  cross-cuts,  and 


FIG.  35.  —  SINGLE-PIECE  SET. 

drifts.  An  adit,  usually  miscalled  tunnel  throughout  the  West, 
is  a  horizontal  tramway  driven  either  within  or  from  without  the 
ore  deposit,  and  connecting  the  interior  workings  of  the  mine 
with  the  surface,  while  an  adit-level  in  contradistinction  includes 
only  those  portions  which  are  contiguous  to  and  immediately 
connected  with  the  adit,  and  are  operated  through  it.  A  drift  is 
a  horizontal  opening  driven  longitudinally  with  and  in  the  ore- 
body,  its  function  being  to  afford  a  means  of  communication  along 
the  lode.  A  cross-cut  is  that  part  of  a  level  which  is  driven  laterally 
across  the  country  formation,  or  across  the  ore  deposit  to  connect 
one  part  of  the  mine  with  another.  The  methods  of  timbering  these 
various  openings  are  identical,  and  will  be  treated  under  one  head. 


MINE  TIMBERING 


37 


The  timbering  of  levels  is  accomplished  by  what  is  known  as 
the  single-piece,  or  the  two-,  three-,  or  four-piece  set,  depending 
upon  whether  one,  two,  three,  or  four  timbers  are  employed. 
They  are  also  known  as  the  quarter,  half,  three-quarter  and  full 
set.  The  pieces  are  known  as  the  post,  if  approximately  vertical, 
the  stull  if  inclined,  the  cap  or  top  piece,  and  the  sill  or  bottom 
piece.  Upon  the  latter  rest  the  posts  of  the  four-piece  set,  the 
sill  being  used  to  keep  the  feet  of  the  posts  of  a  set  from  being 
forced  inward  by  exterior  pressure,  and  also  where  the  ground 
beneath  will  not  support  the  weight  resting  upon  the  set. 


FIG.  36.  —  TWO-PIECE  SET. 

Where  the  sides  of  a  drift  are  sufficiently  strong,  when  the 
deposit  is  of  a  width  of  not  more  than  from  15  to  20  ft.,  a  single 
piece  is  frequently  used.  (See  Fig.  35.)  Should  either  of  the 
walls  prove  to  be  weak,  this  single  piece  is  supported  at  either 
end  as  shown  in  Fig.  36,  forming  what  is  called  the  two-piece  set. 
If  both  walls  are  too  weak  to  support  the  single  piece,  or  should 
the  deposit  be  of  considerable  width,  posts  are  placed  under  both 
ends,  somewhat  as  shown  in  Fig.  37,  forming  the  three-piece  set. 
This  set  is,  however,  usually  made  from  framed  timbers,  either 
round  or  squared;  the  posts  of  the  set  being  of  equal  length,  and 
the  sets  nearly  or  quite  of  equal  size.  These  sets  are  held  in  position 
by  distance  pieces,  either  of  poles  sledged  into  position  between 
the  sets,  or  of  squared  timber,  in  which  case  the  sets  are  framed 
with  a  hitch  to  receive  and  support  the  ends  of  the  piece.  Poles 


38 


MINE  TIMBERING 


used  for  this  purpose  are  called  "sprags,"  while  the  square  pieces 
are  known  as  "girts."  The  framing  of  squared  or  round  timbers 
for  this  set  is  practically  identical,  but  round  timbers  because  of 


FIG.  37.  —  THREE-PIECE  SET. 

their  unevenness  usually  require  that  a  pattern  shall  be  made  as 
an  aid  to  systematic  framing.  The  three-piece  set  is  usually 
made  of  round  timbers,  with  the  posts  set  with  a  spread  or  slant 
outward  at  the  bottom  as  an  aid  to  resist  the  outside  pressure. 


FIG.  38.  —  THREE-PIECE  SET. 

The  feet  of  the  posts  are  set  into  hitches  or  rests  at  the  floor  of 
the  level;  this  also  tends  to  strengthen  the  set  against  the  inthrust. 
(Fig.  38,  a  and  6.) 

The  four-piece  set  is  usually  framed  from  squared  timbers, 


MINE  TIMBERING 


39 


the  posts  being  set  upright,  making  the  square  set,  or  with  a  slant 
outward  as  in  the  three-piece  set.  The  set  consists  of  the  cap, 
sill,  and  two  posts,  usually  carefully  framed.  In  adits  the  set  is 
often  alined  with  considerable  exactness,  and  when  thus  placed 
the  passage  presents  a  pleasing  appearance.  In  adits  and  cross- 
cuts the  posts  are  usually  given  a  slant.  Often,  however,  this  set 
becomes  an  integral  part  of  the  regular  square-set  system  as 
applied  to  the  extraction  of  masses  on  the  levels  and  in  the  stopes 
of  the  large  metal  mines.  (See  Fig.  38,  a,  6  and  c.)  The  framing  of 
this  set  often  becomes  massive,  especially  in  the  heavier  ground 
of  adits.  A  center  post  is  often  placed  in  position  for  forming 
the  double  tramways.  (Fig.  39.) 


W//y/y//////y///w/w 

FIG.  39.  —  FOUR-PIECE  SET. 

The  ground  between  the  sets  is  held  in  place  by  lagging  of 
poles  or  sawed  plank,  which  rests  at  either  end  upon  the  timbers. 
Being  of  comparatively  small  strength  a  lining  of  this  character 
will  yield  to  unusual  pressure,  and  thus  give  evidence  of  incipient 
crushing  that  would  soon  destroy  the  timbers  if  not  attended  to. 

Timbering  Levels  in  Loose  Ground.  —  For  this  purpose  the 
process  known  as  spiling  or  forepoling  is  employed,  its  use  being 
somewhat  similar  to  that  described  under  one-compartment  shafts. 
The  spiling  may  be  of  sawed  plank  or  of  poles  of  the  required 
length,  sharpened  at  the  forward  ends,  and  with  their  heads 
protected  by  an  iron  shoe  when  necessary.  A  set  having  been 
fixed  in  position  (see  Fig.  40)  a  bridge  y  is  placed  upon  the  cap 
supported  by  the  blocks  x  at  either  end.  Between  this  bridge 
and  the  cap  the  spiling  z  is  started,  sloping  upward  at  an  angle. 


40 


MINE  TIMBERING 


As  it  is  driven  forward,  piece  by  piece,  the  material  is  picked 
away  from  the  point  of  each  plank  as  it  is  forced  ahead  a  short 
distance  at  a  time.  In  this  manner  the  entire  shield  is  advanced 
through  successive  small  stages  until  it  has  been  driven  forward 
through  about  half  the  distance  to  its  final  position,  when  a  tem- 
porary false  set,  a,  is  located  to  support  the  spiling.  The  driving 
is  then  continued  until  the  shield  has  been  advanced  to  its  place. 
The  regular  set  is  then  fixed  in  position,  a  bridge  is  placed  upon 
its  cap,  and  the  false  set  removed,  which  allows  the  spiling  to  settle 
upon  the  bridge.  The  same  process  is  continued  in  excavating 
for  the  succeeding  sets  while  passing  through  similar  material 
until  more  solid  ground  is  reached.  When  necessary  the  same 


FIG.  40.  —  SPILING  IN  LOOSE  GROUND. 

process  is  also  applied  to  the  sides  of  the  opening,  bridging  the 
posts  in  the  same  manner  as  the  cap  is  bridged  and  similarly 
advancing  the  shield.  In  very  soft  ground  it  is  sometimes  neces- 
sary to  employ  the  same  method  in  carrying  the  bottom  of  the 
level  forward.  In  very  soft  or  running  ground  the  edges  of  the 
plank  spiling  must  fit  closely  against  each  other,  and  at  the  same 
time  the  face  of  the  working  is  retained  by  breast  boards  held  in 
position  by  struts  footing  against  the  forward  set.  These  boards 
are  advanced  behind  the  forward  edge  of  the  shield,  being  re- 
moved one  at  a  time,  and  placed  farther  ahead  as  the  material 
is  removed  from  in  front  of  it,  a  longer  strut  being  used  to  support 
it  in  its  new  position. 


MINE  TIMBERING 


41 


TIMBERING  OF  THE  WORKING  PLACES  IN  A  MINE. 

As  regards  the  process  of  extracting  the  valuable  materials 
from  their  places  of  deposit  there  are  in  use  many  methods  well 
adapted  to  keeping  the  workings  open  under  the  varying  condi- 
tions. Of  these  the  most  simple  are  those  employed  in  the 
horizontal  or  bedded  deposits,  where  often  the  overlying  rocks 
are  of  such  strength  as  to  require  little  support  other  than  that 
furnished  by  the  occasional  pillar  of  ground  left  in  place  for  this 
purpose.  Even  the  material  left  in  these  pillars  is  sometimes 
removed,  and  the  roof  allowed  to  fall,  when  it  can  be  done 
without  injury  to  future  operations. 

Posts.  —  The  method  of  supporting  the  roof 
of  horizontal  deposits  by  posts  or  props  is 
almost  universally  employed,  and  is  the  most 
simple  artificial  means  of  keeping  open  the  work- 
ing places  of  mines  of  this  character.  These 
posts  are  formed  of  sections  of  trees  of  various 
diameters  and  of  lengths  up  to  20  ft.  They 
are  placed  in  a  vertical  position,  normal  to  the 
roof  and  floor  of  the  deposit,  with  a  flat  plank, 
called  a  cap  piece  or  head  board,  placed  upon  the 
top  of  each  prop  to  distribute  the  pressure  evenly 
upon  the  timber,  and  to  give  greater  bearing 
HEAD  BOARD,  surface  against  the  rock.  (See  Fig.  41.) 

Cribs.  —  Another  method  employed  is  that  of  cribbing,  or, 
as  it  is  sometimes  called,  penning.  This  consists  of  building  up 
a  crib  or  pen  from  floor  to  roof  of  logs, 
laid  in  pairs  or  in  greater  numbers 
across  each  other.  These  cribs  may 
be  made  solid  if  desired,  but  this  is 
not  often  done,  for  practice  prefers  to 
make  a  single  or  double  pen  and  fill 
its  interior  with  waste  material,  which 
is  usually  at  hand  in  underground 
workings,  and  the  use  of  which  greatly  ^^//////^//////////m 
strengthens  the  crib.  (See  Figs.  42  FIG.  42  — CRIB. 

and  43.)  The  stowing  of  waste  in  underground  excavations 
from  which  the  valuable  materials  have  been  extracted  is  often 
resorted  to  and  forms  a  solid  filling  that  will,  with  comparatively 


POST 


42  MINE  TIMBERING 

little  subsidence,  support  any  pressure.  Waste  filling  is  frequently 
used  in  connection  with  and  as  adjunct  to  the  various  systems 
of  timbering  employed  in  supporting  the  walls  of  ore  and  other 
deposits.  It  forms  the  only  permanent  and  certain  means  of 
retaining  the  walls  of  orebodies  in  approximately  their  original 
position. 

The  metal  mines  of  the  West  for  the  most  part  consist  of  de- 
posits that  dip  below  the  horizontal  at  varying  degrees  up  to  the 
vertical,  the  dip  of  the  blanket  veins  and  other  bedded  deposits 
depending  upon  the  uplift  of  the  enclosing  formations,  while 
that  of  the  fissure  veins  follows  the  course  of  the  fissures  cutting 
through  the  earth's  crust.  Contact  veins  may  present  the  char- 
acteristics of  either  of  the  above  mentioned  classes,  and  the 
chambers  or  isolated  pockets  of  valuable  materials  may  follow 
certain  lines  of  deposit,  or  be  without  regularity  or  regular  form. 


FIG.  43.  —  CRIB  WITH  WASTE  FILLING. 

In  size  these  different  deposits  vary  from  the  deposits  too  small 
to  be  successfully  worked  in  a  commercial  way,  to  immense 
masses  of  ore,  the  extraction  of  which  brings  into  use  all  the 
science  of  the  miner  and  of  mining.  Some  of  the  methods  in  use 
for  timbering  these  excavations,  during  and  after  the  extraction 
of  the  ores,  are  but  the  application  of  old  methods  to  present  use, 
while  other  systems  are  distinctly  modern,  both  in  origin  and 
application. 

Stulls.  —  Of  the  older  methods  there  is  principally  and  pri- 
marily the  stull  system,  which  is  but  the  application  of  the  post 
of  the  flat  deposits  to  the  use  of  the  inclined  veins.  Stulls  are 
almost  universally  employed  in  mining  the  smaller  veins,  with  or 
without  waste  filling  as  an  adjunct.  They  consist  of  sections  of 
trees,  pine,  fir,  oak,  or  other  substantial  woods,  round,  and  peeled 


MINE  TIMBERING 


43 


of  their  bark.  These  sections  are  of  all  lengths  up  to  about 
20  ft.,  as  may  be  required  at  the  points  to  be  timbered,  and  in 
diameter  up  to  about  4  ft.  The  greater  the  diameter  the  greater 
the  strength  of  the  timber.  Length  beyond  certain  limits  de- 
creases the  power  to  resist  pressure,  as  the  piece  is  more  liable 
to  bend  or  buckle  under  the  weight. 

Like  the  post  the  stull  is  placed 
with  a  head  board  to  distribute  the 
pressure,  and  to  give  greater  bear- 
ing surface  to  the  stull  in  supporting 
the  hanging  wall  of  the  deposit, 
while  the  foot  of  the  stull  is 
trimmed  and  squared  to  fit  more 
closely  into  the  "hitch"  cut  into 
the  foot-wall  to  prevent  the  timber 
from  slipping  from  its  place.  (See 
Fig.  44.) 

Unlike  the  post  the  stull  is 
not  located  in  position  in  a  line  normal  to  the  walls  of  the 
deposit,  but  at  an  inclination  thereto  approximating  at  a  certain 
ratio  to  the  dip  of  the  vein,  the  angle  of  underlie  of  the  stull 
(see  Figs.  44  and  50)  being  about  one-fourth  of  the  angle  of 
dip  of  the  deposit,  thus: 


FIG.  44.  —  STULL. 


Dip  of  Vein 

Angle  of  Underlie 
of  Stull 

Dip  of  Vein 

Angle  of  Underlie 
of  Stull 

10° 

2J° 

40° 

10° 

20 

5 

50 

12* 

30 

2 

60 

15 

The  reason  for  this  underlie  of  the  stull  is  that  if  the  piece 
were  placed  at  right  angles  to  the  walls  of  the  vein  a  slight  move- 
ment of  the  hanging  wall  would  cause  the  stull  to  fall.  Also  the 
stull  usually  carries  the  weight  of  waste  filling  above  the  levels, 
and  this  it  would  be  unable  to  do  if  placed  perpendicular  to  the 
wall,  while  this  weight  tends  to  wedge  the  piece  more  tightly 
into  place  if  placed  at  an  angle  above  the  perpendicular  to  the 
walls. 

Where  the  foot-wall  of  the  vein  is  too  weak  to  support  the 
stull  in  position  a  false  stull  is  often  placed  to  transpose  the  ver- 


44 


MINE  TIMBERING 


tical  weight  upon  the  foot  of  the  stull  to  a  diagonal  thrust  against 
the  hanging  walL     (See  Fig.  45.) 

In  wide  veins  stulls  are  often  rein- 
forced, so  as  to  enable  them  to  bear 
both  the  vertical  weight  of  the  waste 
filling  above  and  the  side  pressure  of 
the  walls,  by  what  is  known  as  the 
double-stull  method.  This  consists  of 
false  stulls  placed  beneath  the  stull 
proper,  the  former  being  placed  with 
a  foot-hitch,  and  the  stull,  supported 
in  its  position  by  logs  resting  upon 
FIG.  45.  —  STULL  AND  FALSE  two  or  more  of  the  false  stulls  beneath 
STULL.  to  either  side,  footing  against  the  foot- 

wall  without  a  hitch  to  receive  it.     This  method  is  shown  in 
Fig.  46,  a  being  the  end  view  and  b  the  plan. 


FIG.  46.  —  DOUBLE-STULL  METHOD. 

In  vertical  or  nearly  vertical  veins  it  is  impossible  to  place 
the  stull  in  position  with  the  usual  underlie,  and  some  method 


MINE  TIMBERING 


45 


is  necessary  that  will  change  the  vertical  weight  due  to  waste 
above  into  a  diagonal  thrust  against  the  walls.  This  is  done  as  is 
shown  in  Fig.  47,  a  by  means  of  the  saddle-back  system  of  bracing, 


FIG.  47.  —  SADDLE  BACK  AND  ARCH. 

and  b  by  the  arch  with  key-piece.  This  saddle  back  is  sometimes 
used,  as  in  Fig.  48,  to  carry  the  weight  of  waste  filling  above, 
but  it  is  without  value  to  resist  side  pressure. 


FIG.  48.  —  SADDLE  BACK. 

Penning.  —  A  method  of  timbering  known  as  penning  is  some- 
times employed  in  the  inclined  veins,  and  is  nothing  more  than 
the  crib  of  the  flat  deposits  applied  to  the  incline.  It  consists 
of  cribs  of  logs  built  up  from  the  foot-wall  of  the  vein  to  the 
hanging  wall,  which  it  supports.  Occasional  longer  timbers  are 


46 


MINE  TIMBERING 


used  to  tie  the  cribs  together,  and  for  the  purpose  of  forming 
sills  and  caps  for  the  passageways  of  the  mine,  as  shown  in  Fig.  49. 
This  method  of  using  timbers  for  keeping  open  the  working  places 
of  a  mine  is  expensive,  and  requires  quantities  of  timbering,  but 
in  connection  with  waste  filling  it  is  about  as  permanent  as  any 
method  of  timbering  can  be.  It  also  has  the  advantage  of  a 
certain  flexibility  without  weakening  during  movement. 


FIG.  49.  —  PENNING. 

Square  Sets  in  Sloping.  —  This  system  of  timbering  is  pecu- 
liarly adapted  to  the  extraction  of  ores  occurring  in  large  masses. 
In  fact,  the  size  of  the  deposit  matters  little  if  waste  filling  be  used 
in  connection  with  the  sets.  The  method  requires  vast  quantities 
of  timber,  and  the  framing  of  the  pieces  is  no  small  item  of  ex- 
pense, but  the  handiness  of  the  system  is  so  great,  and  its  adap- 
tability to  all  the  needs  of  mining  operations  in  extracting  the 
valuable  materials  from  their  places  of  deposit  is  such  that  it  has 
replaced  many  of  the  cheaper  systems  of  timbering.  Indeed,  it 
is  a  fact  that  its  use  in  large  operations  is  often  found  to  be 
cheaper  in  the  end  than  are  many  of  the  supposedly  more  eco- 


MINE  TIMBERING 


47 


nomical  methods,  and  this  in  spite  of  the  fact  that  the  framing 
of  the  sets  involves  no  small  item  of  outlay.  Briefly,  the  system 
consists  in  filling  up  the  excavations  resulting  from  the  extraction 
of  ores  with  what  might  be  termed  open  blocks  or  cells  of  timber 
that  may  be  added  to  and  extended  indefinitely  in  every  direction, 
lengthwise  of  the  deposit,  across  it,  and  between  the  levels,  while 
the  slope  of  the  body  matters  little  for  the  reason  that,  in  following 
the  ores  between  their  walls,  sets  may  be  extended  laterally 


FIG.  50.  —  ANGLE  OF  UNDERLIE  OF  STULLS. 

outward  from  the  main  body  of  the  timbering  at  any  point  of 
the  foot-wall,  or  left  out  when  the  slope  of  the  hanging  rock 
encroaches  upon  the  timbering. 

The  set  is  made  up  of  posts,  cap,  and  girt,  the  former  being  as 
usual  placed  in  an  upright  position,  in  line  with  the  posts  above 
and  below.  The  cap  rests  upon  the  top  of  the  post,  and  is  in- 
variably placed  across  the  deposit,  the  cap  of  one  set  becoming 
in  effect  the  sill  of  the  set  next  above;  while  the  girt,  which  like- 
wise is  set  upon  the  post,  is  located  along  or  longitudinally  with 


48 


MINE  TIMBERING 


the  run  of  the  orebody.  The  sets  are,  in  the  best  practice,  framed 
for  a  hight  of  7  ft.  in  the  clear  of  the  timbers;  the  reason  for  this 
being  that  this  length  obtains  the  full  strength  of  the  frame  at 
the  same  time  that  it  saves  timber  in  the  mine,  and  leaves  suffi- 
cient hight  for  passage  without  inconvenience.  This  hight  also 
allows  of  placing  the  reinforcing  sets  in  position,  and  still  permits 
passageway  if  necessary.  Across  the  deposit  the  caps  are  made 


FIG.  51.  —  SQUARE  SETS  IN  STOPING. 

of  a  length  such  as  will  set  the  posts  5  ft.  apart  in  the  clear  of 
timbers,  which  gives  room  for  working  the  air  drills  in  the  breasts 
of  ore,  and  for  other  work  at  end  points.  Along  the  length  of 
the  orebody  the  girts  are  made  to  separate  the  cross  frames  by 
a  distance  of  4  ft.  6  in.,  adding  somewhat  to  the  number  of  such 
frames  and  thus  giving  greater  resisting  power  to  the  sets  against 
thrust  from  the  side,  from  which  direction  the  maximum  pres- 


MINE  TIMBERING  49 

sure  usually  acts  against  the  timbers.  (See  Fig.  51.)  In  this  figure 
the  method  of  locating  the  sets  is  shown  in  isometric  projection, 
and  also  that  of  placing  the  different  timbers  of  the  system. 

Usually  a  heading  or  drift  is  first  run  along  the  level,  as  near 
to  the  center  of  the  deposit  as  may  be,  although  this  is  not  essen- 
tial, and  along  this  excavation  the  sets  are  placed  from  which  to 
build  up  the  more  extended  timbering.  On  the  floor  of  this  drift 
are  laid  the  two-post  sill  pieces,  the  sill  girts  are  placed  in  posi- 
tion as  is  shown  in  the  figure,  then  the  posts  are  located,  and 
upon  them  is  placed  a  cap  piece  across  the  drift,  while  a  girt 
connects  this  cross  frame  with  the  last  one  placed  in  position. 
The  frame  is  now  blocked  and  wedged  against  the  top  or  back 
of  the  drift,  and  the  set  is  completed.  As  material  is  removed 
from  either  side  of  this  drift,  one-post  sills  are  laid  upon  the 
floor  of  the  excavation  and  penned  to  the  two-post  sills  already 
located,'  a  sill  girt  is  placed,  the  post  set  upon  the  framing  fitted 
to  receive  it,  and  cap  and  girt  hold  its  top  in  position.  It  is 
then  blocked  and  wedged  firmly  against  the  ground  above,  and 
also  from  the  side.  A  2-in.  plank  roofing  is  laid  from  cap  to  cap 
above  the  set,  which  performs  the  functions  of  a  floor  for  the 
set  next  above  as  the  timbering  is  carried  up.  When  the  foot- 
wall  of  the  deposit  is  reached,  the  sets  are  carried  up  along  its 
slope  by  means  of  the  cap-sill,  a  timber  which  combines  the 
functions  of  the  cap  and  the  sill,  also  shown  in  position  in  the 
figure.  Upon  these  cap-sills  as  a  foundation  are  built  up  a  new 
line  of  sets,  and  the  process  is  carried  on  to  any  extent  by  repe- 
tition. Above  the  sill  floor,  as  the  ground  is  excavated,  posts 
are  set  into  the  gains  formed  by  the  framing  of  post,  cap,  and 
girt  beneath,  and  the  timbers  are  continued  upward,  outward, 
and  lengthwise  as  far  as  may  be  necessary.  The  sets  from  one 
level  are  carried  up  to  those  of  the  level  above,  when  short  sets 
are  placed  in  position  to  carry  the  weight  of  the  upper  framing. 

Reinforcing  Sets.  —  When  the  timbering  is  carried  into  un- 
usually heavy  ground,  or  where  it  is  forced  to  carry  a  great 
weight,  it  is  frequently  necessary  to  reinforce  the  sets  across  the 
deposits  in  line  with  the  greatest  pressure,  and  this  is  done  by 
what  is  known  as  the  diagonal  brace,  the  three-piece  set,  the  full 
or  four-piece  set,  the  "N"  frame  brace,  the  "N"  frame  set,  and 
the  "X"  frame  brace.  These  are  all  shown  in  Fig.  51. 

Ore  Chutes.  —  In  delivering  the  ore  from  the  stopes  above  a 


50 


MINE  TIMBERING 


level  to  that  level  so  that  it  may  be  loaded  into  cars  and  carried 
to  the  shaft  for  conveyance  to  the  surface,  a  storage  bin  and 
passageway  combined  is  necessary,  and  this  is  obtained  by  lining 
one  of  the  sets  as  it  is  carried  up  from  the  level  by  a  close  lining  of 
2-  or  3-in.  planking,  preferably  the  latter.  These  bins  are  desig- 
nated as  chutes,  and  the  framing  at  the  bottom  of  them  whereby 
the  ore  is  delivered  into  the  cars  is  called  the  gate  of  the  chute. 
This  is  made  by  constructing  an  inclined  flooring,  with  sides, 
that  shall  project  beyond  the  side  of  the  chute  into  the  tramway 
sufficiently  far  to  allow  the  rock  to  fall  from  it  into  the  car. 
Cross  timbers  are  placed  across  the  chutes  at  varying  hights  of 
about  30  ft.  in  order  to  break  the  fall  of  the  rock  so  that  it  shall 
not  destroy  the  gate  frame.  In  keeping  the  chutes  near  the 
center  of  the  deposit  they  are  as  often  as  is  necessary  offset 
toward  the  floor  wall  on  an  incline  from  one  line  of  sets  to  the 
next  lateral  set  on  the  floor  above. 

Waste  Filling.  —  In  average  ground  no  system  of  timbering 
will  long  sustain  the  walls  of  large  excavations,  and  waste  rock 
from  the  vein  and  walls,  especially  the  hanging  wall,  is  employed 
for  filling  up  the  spaces  between  the  timbers  in  order  to  make  a 
solid  filling  that  shall  hold  the  ground  in  place.  Passageways 
are  strongly  reinforced,  and  the  flooring  is  removed  from  the 
different  floors  when  waste  is  thrown  into  the  excavation  from 
above. 

Methods  of  Framing.  —  There  are 
several  methods  of  framing  the  timbers 
of  square  sets  in  order  that  they  shall 
come  together  from  the  six  directions 
in  a  manner  best  suited  to  the  needs 
of  the  occasion.  Fig.  52  shows  the 
method  of  cutting  the  timbers  in  use 
in  the  Anaconda  mine,  Butte,  Mont., 
a  giving  the  isometric  perspective  of 
the  post,  cap,  and  girt  as  shown 
separately,  b  showing  their  appearance 
when  joined.  The  Eureka  method  of 
framing  is  shown  in  Fig.  53,  and 
is  very  similar  to  the  Anaconda  frame, 
the  latter  having  one  more  section  cut  from  each  side  at 
each  end  of  the  girt.  Both  of  these  methods  are  used  for  opposing 


FIG.  52.  —  ANACONDA  METHOD. 


MINE  TIMBERING 


51 


Eureka  Fra 


pressure  from  the  sides  of  the  veins,  the  caps  abutting  against 
one  another  to  secure  the  greatest  strength  from  the  timbers; 
but  by  transposing  the  timbers  of  this  set,  so 
that  the  posts  shall  rest  end  on  end  upon  one 
another,  vertical  pressure  may  be  best  resisted. 
This  is  shown  in  the  Burlingame  frame  (Fig. 
54),  a  separated   and  b   joined,   which   is  the 
Eureka   framing   with  the   post   of   the   latter 
forming   the   girt   of   the   former,  the    cap   of 
FIG.  53.  — *  EUREKA  the  Eureka  the  post  of  the  former,  and  the  girt 
METHOD.  of  the  Eureka  the  cap  of  the  former.     Fig.  55 

presents  the  Richmond  frame,  which  is 

a    strong     but    complicated     and     ex- 
pensive   joint    in   which    the    cap    and 

post  are  framed  from  12-in.  timbers  and 

the  girt    of    10-in.  pieces.     Usually  the 

Anaconda  and  Eureka  frames  are  made 

of    10-in.  timbers,   the    reinforcing    sets 

and  solid  waste   filling  being  depended 

upon  to  hold  up  the  ground  rather  than 

by   increasing   the   cross-section   of  the 

•timber.    Frequently,  however,  the  upper 

levels  of  a  mine  are  supported  by  8-in. 

pieces,  but  this  is  infrequent  at  the  deeper 

levels.  The  Eureka  framing  is  now  used  in 

some  of  the  Anaconda  mines  as  being 
the  simplest  and  cheapest  method  of 
framing.  Fig.  56  furnishes  the  details  of 
framing  timbers  for  the  Anaconda  set. 
The  square-set  system  of  timbering  was 
originated  to  meet  the  needs  of  the  sit- 
uation as  developed  in  the  workings  of 
the  Ophir  mine,  on  the  Comstock  lode, 
Nevada,  by  Philip  Deidesheimer. 

Important  details  connected  with 
the  methods  of  timbering  herein  de- 
scribed, and  other  systems  now  in  suc- 
cessful operation  among  the  metal  mines 
of  this  country,  are  excluded  from  this 

FIG.  55.— RICHMOND  METHOD,  necessarily  abridged  article. 


FIG.  54.  —  BURLINGAME 
METHOD. 


52 


-10*^     %, 

m\  :fr 


MINE  TIMBERING 

Cao 


irTfi  ""  r~" r 

111  ml 

4i" 


Side 


fl 

5&. 
ll 


Girt- 


Side 


1 


Post 


Sill  Girt 


Top 


tr 


Cap  Sill 


-  -5'-2- 


Top 


.£}'- 


One-Post  Sill 


Side 


H.i 


Top 


Two-Post  Sill 


Side 


-5V— 


Top 


FIG.  56.  —  ANACONDA  METHOD  OF  FRAMING.     Details. 


MINE   TIMBERING 

BY  THE  SQUARE-SET  SYSTEM  AT  ROSSLAND,  B.C. 
BY  BERNARD  MACDONALD 


MINE  TIMBERING   BY  THE   SQUARE-SET   SYSTEM  AT 
ROSSLAND,   B.C.1 

BY  BERNARD  MACDONALD 

IN  mining  operations,  when  the  ore  extracted  exceeds  a  width, 
of  12  or  15  ft.,  it  has  been  found  that  the  cheapest  and  only 
effective  method  of  timbering  is  by  the  square-set  system. 

The  system  may  be  generally  described  as  a  rectangular 
skeleton  framework  of  timbers,  extending  from  wall  to  wall  of 
the  vein  as  exhausted,  the  different  members  of  which  are  so 
framed  as  to  stiffen  and  support  each  other,  and  equalize  and 
distribute  local  strains  after  the  manner  of  a  truss. 

HISTORICAL 

The  square-set  system  of  timbering  was  invented  by  Philip 
Deidesheimer,  while  Superintendent  of  the  Ophir  mine,  on  the 
Comstock  lode,  in  1860. 

In  Monograph  IV  of  the  United  States  Geological  Survey, 
"  Comstock  Mining  and  Miners,"  the  following  reference  is  made, 
which  will  be  found  interesting  under  this  heading: 

"At  the  50-ft.  level  (of  the  Ophir  mine)  the  vein  of  black 
sulphurets  was  only  3  or  4  ft.  thick,  and  could  readily  be 
extracted  through  a  drift  along  its  line,  propping  up  the  walls 
and  roof,  when  necessary,  by  simple  uprights  and  caps.  As  the 
ledge  descended,  the  sulphuret  vein  grew  broader,  until  at  a 
depth  of  175  ft.  it  was  65  ft.  in  width,  and  the  miners  were  at  a 
loss  how  to  proceed,  for  the  ore  was  so  soft  and  crumbling  that 
pillars  could  not  be  left  to  support  the  roof.  They  spliced  timber 
together  to  hold  up  the  caving  ground,  but  these  jointed  props 
were  too  weak  and  illy  supported  to  stand  the  pressure  upon 
them,  and  were  constantly  broken  and  thrown  out  of  place. 

1  From  Proceedings  of  Canadian  Mining  Institute,  1903,  Vol.  6. 

55 


56  MINE  TIMBERING 

The  dilemma  was  a  curious  one.  Surrounded  by  riches,  they 
were  unable  to  carry  them  off. 

"The  company  was  at  a  loss  what  to  do,  but  finally  secured 
the  services  of  Philip  Deidesheimer,  of  Georgetown,  California, 
who  visited  and  inspected  the  treasure-lined  stopes  of  the  Ophir." 

During  Mr.  Deidesheimer's  engagement  at  the  Ophir,  all  the 
principles  of  square-set  timbering  were  evolved  under  his  imme- 
diate supervision,  and  the  wide  and  rich  orebodies  occurring  in 
that  mine  were  successfully  extracted  without  the  loss  of  ore  or 
injury  from  caving  by  the  use  of  this  system.  The  system  was 
then  used  in  all  the  mines  on  the  Comstock  lode,  and  subse- 
quently in  all  metalliferous  mines  elsewhere  where  the  orebodies 
exceed  a  width  of  15  ft.,  the  extreme  width  that  it  is  practical  to 
timber  by  stulling. 

The  "square  set"  has  undergone  numerous  modifications  of 
detail  in  dimensions  and  the  framing  of  its  members  in  the  various 
camps  where  it  has  since  been  used,  owing  mainly  to  local  condi- 
tions, the  dip  of  the  vein,  and  the  character  of  the  orebodies  and 
the  enclosing  rock. 

VEIN  CHARACTERISTICS  AT  ROSSLAND 

In  the  Rossland  mines,  the  ore  deposits  have  widths  ranging 
up  to  100  ft.  or  more,  and  lengths  of  several  hundred  feet  along 
the  veins.  The  veins  are  sheer  zone  fissures,  the  vein-filling 
consisting  of  country  rock,  which  is  now  found  replaced,  and 
cemented  to  various  degrees  of  completeness  by  auriferous  pyr- 
rhotite  and  chalcopyrite. 

The  ore  and  the  enclosing  rock  may  be  designated  as  extremely 
hard,  and  the  veins  dip  at  angles  of  about  70  deg.  These  condi- 
tions facilitate  and  simplify  timbering,  without,  however,  doing 
away  with  its  necessity. 

PRELIMINARY  WORK 

In  stoping  out  these  deposits,  the  work  is  begun  at  the' level 
drives  or  drifts  run  in  the  vein,  and  continued  upward  in  steps 
or  stopes. 

The  first  work  in  opening  up  an  ore  shoot  or  deposit  prepara- 
tory to  extraction  consists  of  running  drives  or  drifts  through  it 
from  the  level  stations  at  the  shaft,  which  are  generally  cut  at 


MINE  TIMBERING  57 

distances  of  from  100  to  200  ft.  in  depth  below  each  other.  Such 
drives  may  happen  to  be  run  along  either  wall  of  the  vein,  or 
through  the  vein  at  any  point  or  distance  (usually  varying)  from 
either  wall. 

These  drives  are  considered  as  random  bores,  made  longitu- 
dinally through  the  vein  to  determine,  in  a  general  way,  its 
course  or  strike,  and  the  behavior  and  characteristics  of  the  ore 
shoot.  They  serve,  besides,  as  preliminary  thoroughfares  for  the 
traffic,  drainage  and  ventilation  necessary  for  the  preparatory 
work  of  stoping,  to  be  hereafter  described. 

As  generally  run  in  the  LeRoi  vein,  the  drives  have  widths  of 
about  6  ft.,  and  hights  of  about  8  ft.,  and  require  no  timbering, 
owing  to  their  comparatively  small  size  and  the  hardness  of  the 
vein  rock. 

When  it  is  decided  to  begin  stoping  on  any  new  level,  the  first 
work  done  is  to  excavate  the  ore  along  the  drives  from  wall  to 
wall  of  the  vein,  making  the  excavation  of  sufficient  hight  to 
receive  the  sill  floor  set  of  timbers,  as  the  first  series  of  square 
sets  on  the  level  is  called,  and  to  leave  a  space  of  2  or  3  ft. 
over  the  set.  This  space  serves  to  provide  room  for  blocking 
and  wedging  the  timbers  to  place,  and  to  receive  a  layer  of  old 
timbers,  which  act  as  a  cushion  in  preventing  the  possible  breaking 
of  the  timbers  by  the  masses  of  rock  that  must  be  blasted  down 
on  them,  as  the  work  of  stoping  out  the  ore  above  proceeds. 

SILL  FLOOR  CONSTRUCTION 

The  sill  floor  is  a  framework,  made  of  10x10  =  in.  sawed 
timbers,  laid  down  on  the  working  level  in  the  orebody.  They 
serve  as  the  sills  or  foundation  timbers  on  which  the  square  sets 
are  to  be  erected.  It  is,  therefore,  the  first  as  well  as  the  most 
important  part  of  the  square-set  system  of  timbering. 

Figure  57  shows  the  sill  floor  as  laid  down  and  ready  to  receive 
the  sill  floor  set  of  timbers.  The  members  of  the  sill  floor 
consist  of  three  pieces:  the  stringer,  or  long  sill;  the  spreader,  or 
short  sill ;  and  the  butt  spreader,  or  brace.  These  members,  when 
repeatedly  laid  in  duplicate,  will  make  up  a  sill  floor  to  any 
extent  required  by  the  size  of  the  deposit. 

The  dimensions  and  details  of  the  framing  of  these  members 
are  also  shown  in  the  figure. 


58 


MINE  TIMBERING 


Cross  Section 

\^ 

\\ 

*\v 

_^ 

—  ^ 

— 

1 

\    ' 

"    Short  Sill      { 

!    Ip:  5  •' 

s 

~ 

" 

I 

I 

j 

„ 

j    .' 

V 

5-4^  1- 

> 

El£ 

j                       i 

//, 

'f 

r/ 

Plan  of  Sill  Floor 

FIG.  57.  —  SQUARE-SET  TIMBERING  AT  ROSSLAND,  B.C. 


MINE  TIMBERING  59 

The  long  sill  measures  15  ft.  over  all,  and  is  framed  from  a 
16-ft.  timber,  which  allows  6  in.  to  be  cut  from  either  end  to 
square  the  piece  and  remove  sun  cracks. 

The  short  sill,  as  framed,  measures  5  ft.  4  in.  in  length,  over 
all,  three  of  which  may  be  cut  from  a  16-ft.  timber,  if  it  over- 
measures  a  few  inches,  as  it  generally  does,  and  the  ends  are 
sound. 

The  butt  sill  or  brace  is  framed  of  varying  lengths  to  suit  the 
existing  space,  which  generally  varies  owing  to  local  bulgings  or 
contractions  of  the  vein.  It  is  framed  on  one  end  exactly  like 
the  short  sill,  while  the  other  is  cut  square  or  beveled  to  fit  or 
butt  against  the  wall-rock,  from  which  it  is  wedged  tightly  to 
place  against  the  long  sills. 

A  description  of  the  method  of  framing  the  sill  floor  set  of 
timbers  is  not  needed,  as  it  will  be  fully  comprehended  by  a 
glance  at  the  figure. 

In  laying  the  sill  floor,  the  long  sills  are  set  ends  abutting 
flush  against  each  other,  and  as  nearly  as  possible  parallel  with 
the  general  strike  of  the  vein,  ignoring  any  local  bulging  of  the 
walls. 

The  first  sill  is  laid  close  and  approximately  parallel  to  the 
foot-wall,  in  which  position  it  is  leveled  and  held  by  blocking  or 
butt  braces;  the  other  long  sills  are  laid  paralleling  this  one  at 
proper  distances  apart,  that  is,  5  ft.  4- in.  between  centers.  The 
cross  sills  fit  on  top  of  these,  lying  level  with  them,  the  ends  being 
halved  in  framing  to  rest  into  similar  halvings  in  the  long  sills, 
and  to  abut  flush  against  each  other  and  extend  endwise  from 
wall  to  wall  of  the  vein. 

When  the  long  sills  reach  as  near  the  hanging  wall  of  the 
vein  as  desirable,  they  are  braced  from  it  by  the  butt  spreaders 
or  by  blocking,  wedged  tightly  to  bring  all  the  members  into 
proper  position.  The  philosophy  of  this  design  of  the  sill  floor 
is  as  follows : 

The  long  sill  is  made  15  ft.  in  length,  so  as  to  better  sustain 
the  superstructure  of  square  sets  erected  on  it  when  the  ore  upon 
which  it  rests  comes  to  be  stoped  away.  For  instance,  when  the 
ore  is  being  blasted  from  under  the  sill  floor  by  the  work  of  stoping 
coming  from  the  level  below,  and  the  blasting  tears  away  a  por- 
tion of  the  ore  upon  which  the  sill  floor  rests,  making  an  opening, 
as  it  generally  does,  of,  say,  8x8  ft.,  the  long  sills  would  over- 


60 


MINE  TIMBERING 


reach  such  opening,  and  one  or  both  ends  would  rest  on  the 
solid  rock  beyond.  Nor  would  the  short  sills  drop  away  through 
such  opening,  owing  to  the  fact  that  they  rest  on  the  top  of  the 
long  sills,  as  previously  described  and  shown  in  the  figure. 

Through  the  opening  thus  made  in  the  ore,  the  portion  of  the 
sill  floor  exposed  would  be  supported  by  posts  set  on  the  timber 
sets  in  the  stope  below.  Thus  the  long  sill  operates  to  allow 
the  work  of  stoping  out  the  ore  upon  which  the  sill  floor  rests 
to  be  safely  conducted,  if  such  portions  of  the  sill  floor  as  become 
exposed  as  the  work  proceeds  are  properly  supported  by  posts 
from  the  timber  work  underneath. 


THeal  Longitudinal  Section    » 

nn    nn     n       n     nndOR  O  n  n  n  n 


t^*?rtsOTmn^^J«*w  \<^W 

>'^ 

FIG.  58.  —  WORKING  FLOORS  AT  ROSSLAND,  B.C. 


TIMBERS  AND  METHODS  USED  AFTER  SILL  FLOOR  is  LAID 

The  first  tier  of  square  sets  erected  on  the  sill  floor  is  known 
as  the  "sill  floor  sets."  The  assemblage  of  the  framed  timbers 
into  square  sets  then  proceeds  upward,  by  floors,  set  over  set, 
vertically,  pari  passu  as  the  work  of  stoping  exhausts  the  vein. 
The  timber  structure  over  any  level  is  referred  to  in  subdivisions 
as  the  "sill  floor  sets,"  "first  floor  sets,"  "second  floor  sets," 
and  so  on  until  it  reaches  the  level  above  and  catches  up  and 
supports  the  sill  floor  on  that  level. 

This  method  of  reference  to  the  timbering  as  it  advances 


MINE  TIMBERING 


61 


carries  with  it  the  data  for  a  general  calculation  of  the  portion 
of  the  vein  exhausted  over  a  level,  as  each  set  of  timbers  in  place 
indicates  that  9  ft.  vertically  and  5£  ft.  horizontally  of  the  vein 
are  exhausted,  9  ft.  being  the  bare  hight  and  5^  ft.  the  width  of 
space  required  for  a  set  of  timbers.  And  each  square  set  in  place 
indicates  that  24  tons  of  vein  matter  have  been  extracted. 

Aside  from  the  sill  floor,  all  the  timbers  employed  in  the 
square-set  system,  except  the  planks  for  floorings  and  chutes,  are 
framed  from  round  logs.  These  logs  are  preferably  of  red  fir,  it 
being  the  strongest  native  timber,  but  pine,  spruce  and  tamarack 
may  be  used.  When  cut  in  the  woods,  the  logs  are  peeled  and 


Id?al  Cross  Section 

n  n  n  n  n  n  n  n  n  n 


FIG.  59.  —  WORKING  FLOORS  AT  ROSSLAND,  B.C. 

allowed  to  season  for  a  period  of  from  six  to  twelve  months, 
during  which  time  they  lose  about  one-third  of  their  green  weight, 
which  is  a  very  important  advantage  in  subsequent  handling. 
In  diameter,  they  range  from  12  to  20  in.,  but  generally  average 
about  16  in.,  and  are  sawed  in  lengths  of  16  ft.  6  in. 

The  logs  may  be  framed  by  hand  or  with  machine  saws  into 
the  various  members  of  the  square  set,  as  follows,  viz.:  posts, 
caps,  girts  or  braces,  and  butt  caps.  Like  the  members  of  the 
sill  floor,  these  members  may  be  duplicated  to  any  extent  required 
by  the  size  of  the  excavation  to  be  timbered. 

The  posts  as  framed  are  8  ft.  2  in.  over  all;  the  caps  are  5  ft. 


62  MINE  TIMBERING 

4  in.,  and  the  girts  or  braces  are  5  ft.;  the  butt  caps,  like  the  butt 
spreaders  on  the  sill  floor,  are  cut  in  varying  lengths  to  suit  such 
spaces  as  may  exist. 

The  details  of  framing  the  logs  into  members  of  the  square 
set  are  plainly  shown  in  Figs.  57  to  63,  and  need  no  further 
description.  The  philosophy  of  this  method  of  framing  the 
timbers  is  that  the  cap  pieces  of  the  various  sets  form  continuous 
stringers  of  timbers  running  horizontally  from  wall  to  wall  of  the 
vein,  no  matter  what  this  distance  may  be.  Such  stringers  offer 
the  end  grain  or  greatest  strength  of  the  timbers  to  the  walls, 
from  which  the  greatest  strains  are  generated.  The  posts  and 
girts  rigidly  support  the  stringers  thus  formed  of  the  several 
cap  pieces  in  true  horizontal  position,  bearing  on  the  joints  from 
right-angled  directions,  while  the  cap  pieces  and  the  girts  support 
the  posts  in  true  vertical  position. 

The  whole  framework  forms  a  strong,  rigid  structure,  capable 
of  indefinite  extension  upward  and  longitudinally  as  stoping 
proceeds,  allowing  at  the  same  time  for  any  expansion  and  con- 
traction in  width  to  suit  such  irregular  widths  of  the  vein  as  may 
occur. 

Besides  the  functions  of  the  various  members  of  the  square- 
set  system  to  support  each  other  in  the  manner  described,  that 
of  the  cap  pieces  is  to  receive  directly  and  sustain  the  strains 
coming  from  the  walls  of  the  exhausted  deposit,  while  that  of 
the  posts  is  to  support  the  vertical  weight  coming  from  the  un- 
dercut ore  deposit  and  the  broken  ore  lying  on  the  floors,  but 
strains  coming  from  any  direction  are  distributed  over  all  the 
members  of  the  set. 

The  system  possesses,  to  a  considerable  degree,  the  qualities 
of  a  truss,  and  makes  it  possible  to  extract  all  the  ore  of  any 
deposit  and  effectually  secure  the  enclosing  walls  from  caving  in. 
When  the  framework  comprising  the  sets  is  erected,  a  floor, 
consisting  of  3-in.  plank,  is  spiked  down  on  the  caps  of  each 
floor  set.  These  are  the  working  floors  on  which  the  miners 
operate  the  machine  drills,  in  the  method  shown  in  Fig.  58. 
When  the  ore  is  dislodged  from  the  vein  by  blasting,  it  falls  on 
these  floors,  where  the  waste  or  second-class  ore  may  be  sorted 
out  from  the  shipping  ore.  The  shipping  ore  is  shoveled  into 
chutes  which  are  built  of  4-in.  plank  spiked  to  the  timber  frame- 
work and  carried  upward  with  the  square  sets,  as  shown  in  the 


MINE  TIMBERING  63 

figures.  The  second-class  ore,  or  waste  sorted  out,  may  be  stored 
temporarily  or  permanently  in  the  framework  of  the  timbering, 
from  whence  it  may  be  drawn  off  at  any  time  through  chutes, 
should  removal  elsewhere  be  desired. 

Figures  58  and  59  are  ideal  longitudinal  and  cross-sections 
illustrating  the  method  of  timbering  and  the  work  of  stoping  as 
it  is  carried  on  between  the  levels.  The  original  position  of 
the  level  drive,  as  already  stated,  furnishes  the  point  from  which 
the  excavation  of  the  vein  matter  for  the  sill  floor  is  commenced. 

The  step  method  of  excavating  the  ore  is  shown  in  Fig.  58, 
where  stoping  is  proceeding  in  double-headed  steps,  each  step 
excavating  the  ore  from  wall  to  wall  and  having  a  vertical  hight 
of  9  ft.  in  the  clear,  which  allows  of  the  erection  of  one  floor  of 
timber  sets,  which  in  turn  provides  the  scaffolding  from  which 
the  miners  may  attack  the  ore  above. 

In  stoping  out  the  ore  on  any  level,  the  ordinary  method  is 
to  keep  the  sill  floor  at  least  30  ft.  in  advance  of  the  first  floor, 
and  it  about  30  ft.  in  advance  of  the  second,  and  so  on,  as  is  shown 
in  Fig.  58.  One  machine  drill,  or  generally  two,  in  case  the  vein 
is  wide,  are  assigned  to  work  the  two  opposite  headings  of  any 
floor,  going  in  opposite  directions,  working  on  each  heading  alter- 
nately. When  one  face  is  drilled  and  blasted,  the  machine  drills 
are  changed  to  the  opposite  face,  and  the  shovelers  pass  the 
broken  rock  into  the  chutes,  or  sort  it,  if  sorting  is  required. 
When  the  ore  broken  is  thus  removed  from  the  face  the  timber 
gang  erects  another  unit  of  timber  there,  and  the  stope  is  again 
in  readiness  for  the  machine  drills,  which  have  by  this  time 
finished  drilling  on  the  opposite  face. 

Generally  the  step  method  of  stoping  proceeds  in  opposite 
directions  from  a  raise  run  through  the  orebody  between  the 
levels,  as  shown  in  Fig.  59.  The  framed  timbers  are  delivered  in 
the  stope  by  dropping  them  down  through  this  raise  or  hoisting 
them  from  the  level.  Sometimes  the  framed  ends  of  the  timbers 
are  injured  by  dropping  them  through  the  raise,  but  as  a  rule  no 
material  injury  is  done  to  them,  while  the  time  gained  by  this 
method  is  a  very  important  factor  in  cheapening  the  cost  of 
timbering,  compared  with  hoisting  piece  by  piece  from  the  sill 
floors  underneath. 


64  MINE  TIMBERING 


PER  TONNAGE  COST  OF  SQUARE-SET  TIMBERING 

After  the  sill  floor  is  laid  and  the  framework  started,  a  square 
set,  which  is  made  up  of  one  post,  one  cap,  and  the  brace,  consumes 
18  ft.  6  in.  running  feet  of  logs. 

The  logs  peeled  and  seasoned  cut  measuring  16  ft.  6  in.  cost 
$1.20  each  delivered  f.o.b.  the  cars  at  the  works,  or  about  8c. 
per  running  foot.  Therefore,  the  18  ft.  6  in.  required  for  the  set 
would  cost  $1.48,  or  say  $1.50,  unloaded  in  the  framing  shed, 
provided  the  logs  are  not  cut  to  waste  in  framing,  which  may  be 
avoided  with  a  little  care  and  foresight. 

The  cost  of  framing  the  pieces  comprising  the  set  would  be 
about  $0.553,  when  framed  by  hand  labor,  carpenters  being  paid 
$3.50  per  day  of  nine  hours. 

COST  DATA  PER  SQUARE  SET,  HAND  FRAMED 

Material.  —  A  log,  measuring  16  ft.  6  in.,  costing  $1.20,  cuts 
into  two  posts,  or  three  caps,  or  three  braces;  therefore: 

Material  in  one  post  costs  .........................  $0.65.0 

Material  in  one  cap  costs  .........................  0.43.0 

Material  in  one  brace  costs  .......................  0.43.0 

Total  cost  of  material  in  one  set  is,  say  ............  $1.50.0 

Labor.  —  One  carpenter  (wages  $3.50)  frames  per  day: 

About  21  posts,  costing  each  ......................  $0.16.7 

About  21  braces,  costing  each  .....................  0.16.7 

About  16  caps,  costing  each  .................  ......  0.21.9 

Total  cost  for  framing  ............................  $0.55.3 

Total  cost  of  labor  and  material  in  set  .............  $2.05.3 

The  details  of  cost  of  the  individual  members  of  the  set  framed 
on  the  surface,  ready  to  go  into  the  mine,  are  therefore  as  follows  : 

{  Material  .......     $0.65.0  ltt, 

1  post  costs,  for.  ...  |  Labor  ..............       Q  16  ?  ]$0.81.7 


,      ,  J  Material  ............       0.43.0  1  -         Q 

1  cap  costs,  for  .  .  .  .  {  Labor  ..............       Q  ^  g  ]$0.64.9 

f  Material  ............       0.42.0  Ln  _Q  . 

1  brace  costs,  for.  ..  j   T   ,  n  1A  -     $0.58.7 

I  Labor  ..............       0.16.7  J 

Making  the  total  cost  ....................  .  .......     $2.05.3 

The   costs   next   attaching  to   the   square  set,   or  unit,  of  this 
method  of  timbering  are  : 


MINE  TIMBERING  65 

Lowering  into  the  mine approximately  $0.10 

Delivering  to  place  required approximately    0.10 

Labor  in  erecting approximately    1.50 

Incidental  material,  such  as  blocks,  wegdes,  tools,  nails. approximately    0.10 
Cost  of  sill  floor  averaged  over  11  sets  between  levels 

100  ft.  apart  approximately    0.15 

$L95 

These  costs  last  given  above  may  vary  greatly,  being  in- 
creased or  decreased  with  the  completeness  of  the  facilities  for 
handling  the  framed  timbers;  the  cost  of  the  several  items  as 
stated  may  vary  accordingly  from  time  to  time,  but  the  total 
will  be  about  the  average  cost,  and  will  closely  approximate  that 
of  carefully  supervised  operations.  Therefore,  from  the  fore- 
going it  will  be  seen  that  the  cost  of  the  square  set  placed  in  the 
mine  will  come  down,  as  follows: 

Total  cost  of  labor  and  material,  as  above $2.05.3 

Labor  and  material  when  set  is  in  place,  as  above ...       1.95.0 
Total  cost,  say $4.00.0 

When  framed  by  machine  saws,  the  cost  of  framing  a  square  set 
does  not  exceed  30c.,  including  the  cost  of  power,  as  against  55c.  by 
hand,  a  difference  of  25c.  per  set.  Therefore,  if  the  framing  is  done 
by  machinery,  the  cost  of  a  set  in  place  would  be  S3. 75  as  against 
$4  as  shown  above  when  the  framing  is  done  by  hand  work. 

The  per  tonnage  cost  for  timbering  by  this  method  works  out 
as  follows :  The  average  space  to  be  excavated  for  each  square  set 
is  5.3  ft.  wide  by  5  ft.  long,  by  9  ft.  in  hight,  or  240  cu.  ft.  The 
Rossland  ores,  being  heavily  impregnated  with  iron  and  copper 
pyrites,  yield  a  ton  of  2000  Ib.  for  each  10  cu.  ft.  of  ore  in  place; 
therefore,  from  the  240  cu.  ft.  of  vein  required  to  be  excavated 
for  a  set  of  timbers,  the  yield  will  be  24  tons.  If  the  timbers 
were. framed  by  hand  the  cost  of  timbering,  so  far  as  described, 
would  be  about  $0.17  per  ton;  if  by  machinery,  $0.15.6,  a  differ- 
ence of  $0.01.4  per  ton  in  favor  of  the  machine-framed  sets. 

In  addition  to  the  costs  above  tabulated,  there  still  remain 
the  costs  of  the  chutes,  floors,  ladders,  and  railings  necessary  for 
the  convenience  and  safety  of  the  miners  and  the  passage  of  ore 
and  supplies.  These  require,  on  an  average,  about  100  ft.  of 
lumber,  board  measure,  per  square  set,  which,  at  $11  per  1000  ft., 
would  add  for  the  lumber  $1.10,  and  for  placing  it,  say  $0.10,  or 
a  total  of  $1.20  to  each  square  set,  which  would  then  cost,  in  the 


MINE  TIMBERING 


case  of  hand  framing,  $5.20,  or  a  total  cost  of  $0.21.6  per  ton  of 
crude  ore;  and  in  the  case  of  machine  framing,  $4.95,  or  a  total 
cost  of  $0.20.6  per  ton  of  crude  ore. 


I 


MINE  TIMBERING  67 

INCIDENTAL  COSTS 

The  cost  of  timbering,  per  ton  of  ore  shipped,  would  be  greater 
than  the  figures  given  above  in  proportion  to  the  quantity  of 
waste  or  second-class  ore  that  would  be  sorted  out  from  the 
crude  ore  extracted. 

In  the  Rossland  mines  about  20  per  cent,  of  the  ore  mined 
is  sorted  out  and  goes  to  the  second-class  ore  dump  to  await 
profitable  treatment,  expected  to  come  in  the  future.  Deducting 
20  per  cent,  of  the  24  tons  of  crude  ore  in  a  square  set,  there 
would  remain  19.20  tons  as  the  shipping  ore,  against  which  the 
total  costs  of  the  square  set  as  above,  $5.20  or  $4.95  as  the  case 
might  be,  would  have  to  be  charged.  This  would  raise  the  per 
tonnage  costs  on  the  ore  shipped  to  about  $0.27  and  $0.26  re- 
spectively. 

Where  there  is  a  reasonable  expectation  that  the  second-class 
ore  will  eventually  pay  a  profit  after  suitable  treatment,  it  would 
be  only  fair  to  charge  a  pro  rated  cost  of  the  timbering  to  it,  and 
the  cost  would  then  remain  $0.20.6  and  $0.21.6  per  ton  as  above. 

In  cases  where,  on  account  of  bad  ground,  angle  bracing, 
bulkheading,  or  cribbing  and  filling  would  be  required,  the  per 
tonnage  cost  would  be  still  further  increased,  but  to  a  compara- 
tively small  extent. 

LIMITATIONS  OF  THE  SQUARE  SET 

The  limit  of  the  capacity  of  the  square-set  system  as  already 
described,  without  any  reinforcing  devices  to  withstand  the 
pressure  that  may  be  exerted  on  it  by  the  enclosing  walls  of  an 
orebody  when  that  orebody  is  extracted,  may  be  reached. 

This  limit  depends  on  the  nature  of  the  walls  enclosing  the 
deposit,  and  the  extent  of  the  excavation.  If  the  wall-rocks  are 
solid  and  do  not  swell  on  exposure  to  the  air  and  dip  at  a  high 
angle,  the  orebody  may  be  extracted  between  levels,  say  100  ft. 
apart  and  for  a  length  of  200  or  300  ft.  along  the  vein,  and  the 
pressure  likely  to  be  exerted  by  the  walls  will  be  sustained  by  the 
skeleton  square  set  without  reinforcement  of  any  kind. 

If,  however,  the  vein  dips  at  a  low  angle,  and  the  wall-rocks 
are  decomposed,  or  of  a  talcose  or  serpentine  character,  and 
disposed  to  swell,  the  pressure  that  might  be  exerted  on  the 
timbers,  when  even  a  comparatively  small  excavation  of  the 


68  MINE  TIMBERING 

orebody  has  been  made,  may  cause  them  to  crush,  "  jack-knife," 
or  collapse,  allowing  the  wall-rocks  to  cave  in  and  close  up  the 
stope.  When  the  members  of  the  square  set  become  squeezed 
out  of  the  truly  right-angled  position  which  they  should  occupy, 
their  capacity  to  resist  wall  pressure  or  strains  from  any  direction 
is  practically  nil. 

When,  owing  to  wall  pressure  or  imperfect  erection  of  the 
sets,  "  jack-knifing "  of  the  square  sets  results,  the  cave-in  which 
sooner  or  later  will  follow,  with  disastrous  consequences,  may  be 
prevented  by  either  bulk-heading,  cribbing,  or  filling  the  skeleton 
framework  of  the  timbers. 

The  cost  of  the  foregoing  methods  of  reinforcement,  which 
are  the  only  practical  ones  that  can  be  successfully  used  in  bad 
ground,  cannot  be  given  with  any  general  degree  of  accuracy,  as 
that  is  so  much  affected  by  the  local  conditions  in  each  case. 

A  general  idea  of  what  the  cost  is  likely  to  be  may  be  gleaned 
from  the  description  following: 

REINFORCEMENT  METHODS 

Angle  bracing.  —  If,  after  the  square  sets  are  properly  erected 
in  place,  the  members  manifest  an  inclination  to  swing  out  of 
the  right-angled  positions  they  originally  occupied  to  each  other, 
this  tendency  may  be  arrested  and  prevented  by  a  system  of 
angle  bracing.  This  consists  of  placing  diagonal  braces  made 
of  round  or  square  timber  on  the  sill  floor  and  against  the  foot 
of  the  posts,  and  leaning  the  heads  so  they  will  fit  snugly  against 
the  top  of  the  posts  underneath  the  caps  or  girts,  as  the  care  may 
be,  of  the  next  adjacent  set.  The  head  of  this  diagonal  brace 
should  lean  in  the  direction  from  which  the  pressure  comes. 
This  method  is  illustrated  in  Fig.  62. 

Cribbing.  —  When  the  square  sets  manifest  a  stronger  ten- 
dency to  swing  than  in  the  case  referred  to,  the  collapse  threatened 
may  be  prevented  by  crib  work.  This  consists  of  crossing  alter- 
nate layers  of  round  or  square  timbers  of  any  convenient  size 
between  the  posts  of  the  sets  until  the  space  between  the  sill  and 
cap  is  filled,  as  shown  in  Fig.  63.  This  crib  work  may  extend 
from  wall  to  wall  through  two  or  more  rows  of  sets  if  required, 
and  the  spaces  between  the  sets  thus  cribbed  may  be  filled  with 
waste  rock,  but  this  is  called  "filling,"  and  will  be  referred  to 
under  that  heading  below. 


MINE  TIMBERING 


69 


70  MINE  TIMBERING 

Bulkheading.  —  This  method  of  reinforcement  consists  of 
placing  timbers  closely  together  in  much  the  same  way  as  the 
crib  work  above  referred  to,  and  wedging  them  tightly  between 
cap  and  sill. 

Filling.  —  This  method  consists  of  filling  the  spaces  between 
the  members  of  the  square  set  with  any  material  such  as  waste 
rock,  earth  or  sand.  When  the  filling  is  done  it  is  retained  within 
proper  bounds,  and  the  necessary  passageways  are  kept  open 
through  the  timbers  by  building  crib  work  around  them  as  de- 
scribed. 

Waste  rock  for  filling  purposes  is  generally  secured  from  the 
development  or  dead-work  that  is  being  prosecuted  in  other 
sections  of  the  mine,  but  where  a  large  quantity  is  required,  it  is 
often  found  necessary  to  mine  it  specially  for  that  purpose,  or 
draw  it  from  the  waste  dumps  on  the  surface.  About  8  cu.  yd. 
of  material  are  required  to  fill  the  vacant  space  of  the  frame  of  a 
square  set,  and  the  cost  of  such  filling  will  be  the  cost  of  obtaining 
and  placing  such  material,  together  with  the  crib  work  required 
to  retain  it  within  proper  bounds. 


GENERAL  REMARKS 

The  square-set  system  of  timbering  is  used  successfully  and 
exclusively  in  all  mines  where  large  deposits  of  metalliferous  ores 
occur. 

Where  favorable  conditions,  such  as  railway  transportation 
and  a  moderate  supply  of  timber,  exist,  it  is  comparatively  cheap. 
If  care  is  taken  in  the  construction  of  this  system  in  the  mine,  it 
ensures  that  all  the  ore  existing  may  be  extracted  without  injury 
to  the  workman  or  the  mine.  Round  logs  or  sawed  timbers  of 
any  dimension,  ranging  from  8  in.  upwards,  may  be  used,  but 
the  sizes  are  governed  by  the  economic  conditions  and  mining 
requirements. 

In  the  mines  of  Rossland,  the  round  logs  or  timbers  used  for 
the  square  sets  cost  $1.20  for  each  log  16.5  ft.  in  length  f.o.b. 
the  framing  shed  at  the  mine.  These  logs  are  cut  in  the  state 
of  Washington,  and  delivered  over  the  Spokane  Falls  and  Northern 
Railway  on  flat  cars,  over  distances  ranging  from  45  to  75  miles, 
each  flat  car  being  loaded  on  an  average  with  60  logs.  The 
unloading  at  the  framing  shed  is  done  in  a  few  minutes  by  cutting 


MINE  TIMBERING  71 

off  the  retaining  standards  on  the  flat  cars,  and  allowing  the 
logs  to  roll  off  on  the  storage  platform. 

Of  course,  where  wagon  transportation  is  required  from  the 
railway  terminus,  the  expense  will  be  correspondingly  increased. 

In  every  mining  camp  there  will  be  more  or  less  variation  in 
the  method  of  framing,  and  in  the  cost  of  the  square  sets  in  place, 
also  in  the  tonnage  of  ore  to  be  extracted  from  the  space  occupied 
by  each  square  set. 

Where  the  dip  of  the  vein  is  at  a  flat  angle  or  the  walls  are 
bad,  shorter  posts  than  those  described  herein  will  probably  be 
more  advantageous;  the  more  vertical  the  dip  of  the  ore  deposit, 
the  longer  the  posts  may  be,  and  vice  versa. 

Where  sawed  lumber  is  comparatively  cheap,  3-in.  plank  is 
preferable  to  lagging  poles  for  floors,  on  account  of  the  better 
floor  it  offers  for  shoveling,  and  the  fact  that  it  may  be  removed 
and  re-used. 


MINING    AND    TIMBERING 

IN    LARGE   OREBODIES  IN  BRITISH    COLUMBIA   AND 

MICHIGAN 

BY  NORMAN  W.   PARLEE 


METHODS  OF  MINING  AND  TIMBERING  IN  LARGE  ORE- 
BODIES   IN   BRITISH   COLUMBIA  AND   MICHIGAN1 

BY  NORMAN  W.  PARLEE 

THE  method  of  mining  to  be  adopted  in  any  particular  mine 
depends  upon  a  number  of  important  considerations.  Among 
these  may  be  mentioned  the  size  and  attitude  of  the  orebody  or 
deposit,  the  hardness  and  rigidity  of  the  ore  and  adjacent  rock, 
the  quantity  and  quality  of  timber  available  and  its  cost,  the 
price  of  labor,  and  the  value  of  the  product  to  be  mined.  Gen- 
erally speaking,  if  a  narrow  vein  is  to  be  worked,  stull  timbers 
are  used,  the  limit  being  a  width  of  about  15  ft.  As  the  vein 
widens  beyond  this,  stulls  are  out  of  the  question,  and  another 
system  must  be  adopted.  The  method  then  employed  may  be 
the  square-set  system,  or  a  filling  method,  except  in  case  of  soft 
ore,  when  a  caving  system  may  be  followed.  There  are  a  great 
many  modifications  of  all  these  systems  to  suit  circumstances 
and  conditions,  and  it  is  the  intention  in  this  paper  to  describe 
and  discuss  them  as  carried  out  in  those  mines  in  which  the 
writer  has  worked,  and  in  which  he  has  become  more  or  less 
familiar  with  the  methods  in  successful  operation. 

The  names  of  the  mines  treated,  and  location,  are  as  follows: 

Le  Roi  mine Rossland,  B.C. 

Old  Ironsides   Phoenix,  B.C. 

Baltic  mine Baltic,  Mich. 

Atlantic  mine Atlantic,  Mich. 

Barnum  mine Ishpeming,  Mich. 

Section  16 Ispheming,  Mich. 

Soft  Ore  Hematite Ishpeming,  Mich. 

Queen  mine Negaunee,  Mich. 

In  nearly  all  these  mines  the  methods  used  apply  principally 
to  mass  mining  in  large  bodies  of  ore.  The  one  exception  is  the 
Atlantic  mine,  which  has  a  narrow  deposit,  and  is  mined  entirely 
by  the  old-fashioned  stull  method. 

1  From  Transactions  of  Canadian  Society  of  Civil  Engineers,  Vol.  18,  1903. 

75 


76  MINE  TIMBERING 

LE  Roi  MINE,  ROSSLAND,  B.C. 

In  this  mine  there  are  one  or  more  veins  or  ore  shoots  of 
varying  width  and  carrying  the  minerals  pyrrhotite,  chalcopyrite 
and  iron  pyrites,  and  mixed  with  these  more  or  less  disseminated 
gold.  It  is  the  gold,  however,  that  affords  the  principal  value 
of  the  ore,  and  without  it  there  would  be  no  Rossland.  The 
vein  is  of  a  pockety  nature  and  some  of  the  pockets  are  of  very 
large  size.  The  dip  is  about  70  deg.,  and  an  incline  shaft  was 
sunk  at  about  this  slope.  As  depth  was  attained  it  was  found 
that  the  vein  pitched  a  little  steeper,  and  the  shaft  was  given  a 
steeper  pitch  also,  thus  forming  what  is  called  a  "knuckle"  in 
the  shaft.  This  knuckle  afterwards  became  a  source  of  consid- 
erable trouble,  because,  at  high  speeds,  the  skip  was  liable  to 
leave  the  track. 

At  intervals  of  100  ft.  drifts  were  run  on  the  lead,  and  the 
deposits  thus  opened  up.  The  first  shaft  had  three  compartments 
timbered  with  the  ordinary  square  shaft  sets.  Sinking  was  car- 
ried on  with  three  shifts  of  miners  working  eight  hours  each,  and 
the  rock  broken  was  hoisted  to  the  level  above  with  a  bucket 
and  air  hoist.  As  the  shaft  became  deeper  the  ore  and  rock 
were  hoisted  by  skips,  run  on  the  balanced  principle.  A  pentice 
of  about  15  ft.  of  rock  was  always  left  in  the  shaft  at  each  level, 
and  served  as  a  protection  to  the  shaft  men  working  below.  It 
was  located  under  the  two  hoisting  compartments,  and  connec- 
tion was  made  below  by  a  passage  at  the  side.  Each  drift  was 
usually  excavated  before  being  timbered. 

At  each  level,  drifts  were  run  on  the  vein  in  the  ordinary 
manner,  dimensions  being  6x9  ft.  In  the  earlier  workings  the 
tracks  were  laid  very  poorly,  and  were  often  the  cause  of  a  great 
deal  of  trouble  and  delay,  when  a  large  output  was  desired.  But 
as  time  passed  improvements  in  this,  and  many  other  respects, 
were  inaugurated,  and  the  tracks  were  laid  to  a  grade  of  from 
7  to  10  in.  per  100  ft.  Track  laying  is  a  very  important  matter 
in  the  economy  of  a  mine,  and  a  good  track  will  always  pay  for 
itself 'many  times  over.  The  tracks  should  not  only  be  good, 
but  there  should  be  plenty  of  them,  placed  so  that  they  will 
be  close  to  the  rock  to  be  removed.  In  drifts  movable  lengths 
of  8  to  10  ft.  should  be  used.  This  saves  shoveling  to  a  long 
distance,  by  placing  them  in  position  as  soon  as  there  is  room, 


MINE  TIMBERING 


77 


and  enables  the  mucker  to  work  to  advantage,  until  there  is 
sufficient  space  for  the  ordinary  16-  to  20-ft.  rails.  The  rails  are 
laid  on  4x6-in.  ties,  3  ft.  in  length,  and  placed  about  4  ft.  apart, 
the  rails  weighing  16  and  20  Ib.  to  the  yard.  The  waste  rock 
encountered  in  development  was  trammed  to  the  shaft  and  sent 


Chute 


Chute 


Elevation  of  Stope 
Plan  Down  Stope 

FIGS.  64-66.  —  STULL  TIMBERING,  LB  Roi  MINE. 

to  the  surface,  though  now  most  of  it  is  filled  into  the  stopes  of 
the  upper  levels. 

When  the  miners  began  to  stope  on  any  level,  an  upright 
post  was  rigged,  and  the  holes  pointed  upward  and  backward. 
On  a  narrow  part  of  the  vein  a  cross  bar  was  often  employed, 


78  MINE  TIMBERING 

which  enabled  the  muckers  to  tram  beneath  from  another  part 
of  the  level,  while  drilling  operations  were  being  prosecuted. 
Whenever  convenient,  however,  the  miners  prefer  to  rig  upright, 
as  they  can  drill  more  advantageously  from  that  position.  As 
they  climbed  higher  on  the  vein,  hitches  were  cut  in  the  foot-wall, 
and  stulls  were  put  in  from  foot-  to  hanging  wall.  One  end  was 
fitted  into  the  hitch,  and  the  other  end  cut  with  such  a  bevel 
that  it  fitted  against  the  hanging  wall,  which  had  been  previously 
faced  if  necessary.  (See  Fig.  65.)  The  greater  the  weight  coming 
on  the  stull,  the  more  securely  it  would  remain  in  place.  These 
stulls  were  placed  tightly  in  position,  and  wedged  if  necessary  or 
possible.  If  there  was  any  liability  of  their  being  knocked  out 
by  blasting,  a  hitch  was  also  cut  in  the  hanging  wall.  Stulls 
were  used  to  form  floors  to  work  from  at  intervals  of  nearly 
20  ft.,  and  such  a  distance  apart  horizontally  that  the  lagging 
placed  upon  them  would  not  be  broken  by  the  blasts  above. 
They  were  also  put  up  against  any  bad  ground  that  required  them. 
The  lagging  used  on  the  stulls  consisted  of  round  poles,  and 
plank  chutes  were  run  up  the  stope  at  convenient  intervals. 

An  idea  of  the  stope  and  chutes  may  be  gathered  from  Figs. 
64  and  66.  A  cross  bar  and  stage  is  shown  in  Fig.  64,  but  usually 
most  of  the  work  is  done  from  the  broken  ore  resting  on  the  stulls, 
and  an  upright  post  is  rigged,  either  on  this  ore  or  on  benches 
on  the  foot-wall. 

But  where  the  orebody  widened,  stulls  could  not  be  used. 
Here  the  stope  was  started  by  enlarging  the  drift  to  the  total 
width  of  the  deposit,  and  a  face  obtained  right  across  the  vein. 
In  one  case  the  width  varied  from  40  to  80  ft.,  and,  as  a  back  or 
roof  of  this  size  would  be  dangerous  to  work  under  without  some 
support,  the  timber  had  to  be  quite  close  to  the  face.  When  the 
muck  was  removed  mud-sills  were  laid  down,  upon  which  the  sill 
posts  were  erected.  These  sills  were  carefully  placed,  and  tamped 
with  fine  dirt.  They  were  braced  apart  by  cross  ties,  and  had  a 
length  of  10  ft.  8  in.,  or  two  sets.  The  framing  and  manner  of 
laying  them  is  shown  in  Fig.  67.  At  first  the  sill  floors  were  not 
planked  over,  but  later  it  was  seen  that  a  plank  floor  was  eco- 
nomical to  shovel  from,  as  often  there  would  be  rock  tumbling 
down,  or  breaking  through  from  the  floors  above. 

On  one  level  in  the  Le  Roi,  the  700-ft.  level,  there  were  no 
fewer  than  eight  machines  working  at  the  same  breast  simulta- 


MINE  TIMBERING 


79 


neously.  This  meant  that  the  rate  of  advance  was  very  rapid, 
and  difficulty  was  experienced  in  keeping  the  timber  close  enough 
to  the  face.  Two  parallel  tracks  were  laid  to  remove  the  ore, 
one  along  the  foot-wall  side  and  one  along  the  hanging  wall  side, 
and  a  large  gang  of  muckers  and  timbermen  became  necessary. 
When  the  sills  had  been  laid  down  square  sets  were  erected  upon 
them,  and  securely  braced  or  spragged.  Spragging  a  set  of 
timber  requires  considerable  experience  on  the  part  of  the  tim- 
berman.  Spraggs  are  pieces  of  round  lagging,  cut  square  at  each 
end  and  of  varying  length,  and  placed  between  the  ground  and 


LL 


Jp 

1- 
\ 

n 

r--V 

ry 

P 
k 

yy: 

FIG.  67.  —  MUD-SILLS  AND  TIES,  LE  Roi  MINE. 

the  caps  or  ties,  as  the  case  may  be,  and  securely  w^edged.  They 
serve  to  keep  the  sets  rigidly  in  their  proper  position,  and  thus 
prevent  them  from  falling  down  during  concussion  after  blasting. 
The  details  of  the  square  sets  are  shown  in  Fig.  68.  These 
were  at  one  time  framed  by  hand,  but  now  a  framing  machine 
does  the  work.  The  sets  are  shown  in  position  in  Fig.  69.  This 
is  a  view  of  a  section  across  a  rather  narrow  part  of  the  vein. 
One  post  on  the  foot-wall  is  placed  in  a  special  manner  to  avoid 
the  necessity  of  cutting  a  large  hitch  in  the  rock,  which  is  very 
hard.  A  hitch  is  often  made  when  it  can  be  cut  without  too 
much  trouble.  On  the  hanging  side  an  extension  cap  is  shown, 


80 


MINE  TIMBERING 


no  hitch  or  support  being  made  for  the  end  of  it.  The  top  "  butt " 
cap  on  the  hanging  side  is  supported  at  the  end  by  a  heavy  pole 
instead  of  a  post.  The  plank  floor,  lagging  and  spraggs  are 
shown  at  the  top. 

The  posts  used  in  the  Le  Roi  ranged  from  12  to  24  in.  in  diam- 
eter, the  caps  12  to  15  in.,  and  the  collar  braces  or  ties  somewhat 
smaller.  In  the  old  days  it  was  the  custom  to  cover  the  caps 


Joint  Across  Vein 


O 


Post 


Sill  Post 


FIG.  68.  —  DETAILS  OF  SQUARE  SETS,  LE  Roi  MINE. 

with  round  lagging,  16  ft.  long  and  up  to  7  in.  in  diameter.  They 
thus  reached  over  three  sets,  but  were  difficult  and  awkward  to 
handle,  on  account  of  their  length.  After  several  years  of  this 
inconvenience  it  was  decided  to  cut  them  so  they  would  reach 
only  two  sets.  The  lagging  was  then  brought  to  the  mine  in 
lengths  of  20  ft.,  and  they  were  sawed  in  half  on  the  surface. 
A  double  tier  of  lagging  was  used,  one  tier  being  laid  on  the  caps 
and  the  other  at  right  angles  to  them.  Still  later  in  the  history 


MINE  TIMBERING 


81 


of  the  mine  3-in.  planks  in  5-ft.  lengths  were  laid  on  the  caps, 
and  a  few  rough  holes  placed  on  top  of  them,  to  prevent  the 
plank  being  broken  by  the  blasts.  These  planks  were  spiked 
with  one  spike  in  each  end,  and  served  to  stiffen  the  timber 
considerably. 

When  the  excavation  on  the  level  had  advanced  a  reasonable 
distance,  say  about  60  ft.,  another  floor  was  started  on  top  of 
the  timber.  Overhand  stoping  now  commenced  and  rock  or  ore 
was  broken  much  more  readily  than  on  the  sill  floor,  as  it  had  a 
better  chance  to  break,  there  being  more  free  surfaces.  Holes 


FIG.  69.  —  SQUARE  SETS  IN  POSITION,  LE  Roi  MINE. 

were  drilled  in  a  face  about  7  or  8  ft.  in  hight,  and  placed  so  as 
to  bring  the  ore  down  to  the  best  advantage,  viz.,  enough  holes 
were  drilled  and  enough  powder  used  to  break  the  ore  to  con- 
venient size  for  economical  handling.  If  it  were  broken  too  fine 
it  would  take  too  long  to  shovel  into  chutes,  while  if  it  came  down 
in  the  form  of  large  boulders  it  was  necessary  to  blast.  The 
sizes  most  conveniently  handled  were  lumps  weighing  from  25  to 
50  lb.,  which  could  be  rapidly  and  easily  thrown  or  pulled  into 
chutes.  The  holes  were  generally  drilled  in  the  direction  of  the 
vein  or  orebody,  and  not  across  it,  the  depth  being  about  7  ft. 
At  each  set-up  the  miners  moved  across  the  face  from  foot  to 


82 


MINE  TIMBERING 


hanging,  or  vice  versa,  as  the  case  might  be.  In  this  way  the 
muckers  cleaned  out  the  broken  ore  behind,  and,  as  soon  as  there 
was  room,  the  timbermen  proceeded  to  put  up  the  timber. 

To  get  out  the  ore,  chutes  were  built  in  every  other  set,  or 

rnTnrrrn 

~~"m          nf    ? 


CM 


wru 


FIGS.  70-72.  —  VIEWS  OF  CHUTE,  LE  Roi  MINE. 

every  third  set  at  most.  The  bed  pieces  were  made  of  8xlO-in. 
timbers,  placed  at  proper  slope  for  the  rock  to  roll  down,  one  end 
being  on  the  collar  brace,  and  the  other  supported  by  a  cross 
piece  inserted  between  the  posts,  and  high  enough  to  enable  the 
one-ton  ore  cars  to  pass  beneath.  Figs.  70  and  72  show  a  front 


MINE  TIMBERING  83 

and  side  view  of  a  chute  respectively.  The  chute  door  or  gate 
consisted  of  a  semicircular  sheet-iron  plate,  with  suitable  stiffen- 
ing to  prevent  deformation,  and  a  lever  attached  by  which  to 
operate  it.  By  means  of  these  chutes  properly  made,  and  with 
dry  ore,  the  car  could  be  filled  in  a  very  few  seconds. 

As  more  floors  were  constructed  above,  the  chutes  were  car- 
ried up  the  full  size  of  a  set,  by  spiking  plank  8  ft.  8  in.  in  length 
on  the  caps  and  collar  braces.  To  bring  them  closer  to  the  ore, 
as  in  a  large  stope,  the  chutes  were  expanded  to  take  in  two, 
three,  and  even  four  or  five  sets.  (See  Fig.  71.)  The  chute 
planks  were  all  placed  vertically,  and  where  it  became  necessary 
a  bottom  of  short  lagging  was  made  for  the  rock  coming  from 
above  to  fall  upon.  A  stiffening  was  made  for  the  chute  planks 
by  a  cross  brace  between  the  posts,  half-way  up  and  well  spiked. 
In  a  wide  stope,  two  rows  of  chutes  and  two  lines  of  track  were 
constructed.  By  this  means  the  muckers  were  enabled  to  get 
the  ore  into  the  chutes  without  being  compelled  to  throw  it  far, 
or  to  use  wheelbarrows  or  any  other  device. 

While  any  level  was  being  developed  a  winze  was  sunk  from 
the  level  above  to  provide  ventilation.  These  winzes  were  always 
located  in  the  stopes,  and  provided  a  sort  of  chimney  by  which 
the  smoke  had  a  chance  to  escape.  They  were  also  used  as  an 
easy  route  by  which  timber  could  be  lowered  to  the  upper  floors, 
and  later,  when  the  ore  had  been  all  removed,  or  nearly  so,  waste 
rock  was  run  in  through  them  to  fill  up  the  stope. 

As  more  and  more  floors  were  attacked  and  carried  forward, 
more  faces  were  worked  simultaneously.  Care  had  to  be  exer- 
cised in  regard  to  approaching  too  near  the  front  line  of  timber. 
The  blasts  might  jar  the  timber,  and  possibly  cause  it  to  throw 
forward  a  few  inches,  even  if  they  would  not  knock  it  down. 
When  square  sets  have  been  disarranged  in  this  manner,  it  is  a 
very  difficult  matter  to  force  them  back  into  position  again. 
I  have  had  occasion,  as  a  timberman,  to  use  jack-screws  in 
cases  of  this  kind,  and  to  spend  considerable  time  on  work 
which,  with  a  little  more  caution  on  the  part  of  the  miners  or  the 
management,  would  have  been  unnecessary.  One  machine  at  a 
face  and  one  machine  at  every  other  floor  appeared  to  be  a  good 
method.  This  allowed  the  men  of  the  timber  gang  to  put  up  a 
line  or  two  of  timber  on  the  intermediate  floors,  and  they  were 
not  interfering  with  either  the  muckers  or  miners. 


84 


MINE  TIMBERING 


An  idea  of  the  method  of  attack  in  a  stope  may  be  gathered 
from  Fig.  73.  In  this  view,  however,  I  have  unfortunately 
shown  the  limit  of  advance  on  each  floor  rather  than  the  actual 
working  condition.  As  illustrated  in  the  diagram  it  would  be 
necessary  to  carry  the  lower  faces  ahead  to  allow  a  chance  to 
work  on  the  upper  ones. 

As  the  floors  became  more  numerous  and  farther  and  farther 
away  from  the  winzes,  some  method  had  to  be  adopted  to  get  the 
timber  into  the  stopes  more  easily,  quickly  and  economically. 
An  excellent  plan  was  introduced  in  the  Le  Roi  in  the  large  stope 
on  the  700-ft.  level.  A  track  was  laid  the  full  length  of  the  stope 


FIG.  73.  —  GENERAL  SCHEME  OF  STOPE,  LE  Roi  MINE. 

on  the  first  floor  above  the  level,  up  out  of  the  way  of  the  tram- 
ming tracks,  and  a  truck  carrying  a  small  air  hoisting  engine 
placed  on  it.  From  the  drum  of  this  hoist  a  manila  rope  was 
carried  up  a  special  timber  chute,  over  a  pulley  on  an  upper 
floor,  and  then  down  the  chute  to  the  level  below.  Here  the 
timber  was  attached  with  a  hook  and  half  hitch,  and  hoisted  to 
any  floor  desired.  An  idea  of  this  arrangement  may  be  gathered 
from  Fig.  73,  in  which  one  timber  chute  is  shown  beside  an  ore 
chute.  The  timber  chutes  were  made  of  2-in.  planks,  spiked  to 
the  collar  braces,  and  inclined  with  the  vein.  They  were  erected 
every  80  ft.  or  less,  and  were  convenient  for  hoisting  drills  and 


MINE  TIMBERING  85 

machines,  as  well  as  timber.  The  timbers  could  be  readily  dragged 
to  any  place  desired  by  means  of  the  "  come-alongs,"  which  were 
a  pair  of  hooks  attached  to  the  center  of  a  small  pipe  3J  ft.  in 
length.  A  man  on  each  end  of  this  pipe  could  drag  a  post  any- 
where over  the  floor. 

The  ore  was  not  sorted  in  the  mine,  but  sent  to  the  surface  to 
be  treated  there.  It  was  trammed  to  the  shaft  and  dumped  into 
large  pockets  from  which  the  skips  were  loaded.  The  tracks  at 
the  shaft  were  laid  directly  over  the  pockets,  and  the  ore  was 
dumped  from  the  car  between  the  rails,  or  at  one  side  of  them. 
These  pockets  were  capable  of  holding  a  good  many  tons,  so  that, 
if  anything  happened  to  the  hoisting  apparatus,  the  trammers 
could  still  work  away,  and  fill  the  pockets.  In  the  new  shaft, 
which  was  put  through  by  means  of  raises  from  each  level,  pockets 
were  made  with  a  capacity  of  about  200  tons. 

From  this  somewhat  detailed  description  it  will  be  seen  that 
a  great  deal  of  timber  is  used  in  this  mine.  The  timber  is  not 
used  merely  to  hold  up  the  hanging  wall  and  roof,  but  principally 
to  furnish  a  convenient  method  of  reaching  all  the  ore,  and  to 
prevent  loose  slabs  and  boulders  from  dropping  on  those  who 
must  work  beneath.  The  workings  are  kept  closely  timbered, 
and  thus  liability  of  accident  is  reduced.  No  staging  is  needed 
in  rigging  machines,  the  muckers  have  a  good  floor  to  shovel 
from,  and  chutes  are  handy  and  convenient,  more  so  than  could 
possibly  be  the  case  in  any  other  mining  method. 

By  this  system  all  the  ore  is  taken  out  between  levels.  The 
sills  of  one  level  are  caught  up  from  beneath,  and  timber  connec- 
tions made  with  the  level  below. 

When  a  stope  or  level  is  worked  out  the  only  timber  saved  is 
the  rough  lagging  and  plank  flooring,  which  is  readily  torn  up 
and  used  again.  Waste  rock  from  development  work  in  other 
parts  of  the  mine  is  dumped  down,  and  the  old  stope  gradually 
filled  up.  This  rock  is  brought  up  from  the  lower  levels  on 
cages  in  the  new  five-compartment  shaft.  No  great  attempt  is 
made,  however,  to  fill  the  stopes. 

OLD  IRONSIDES  MINE,  PHOENIX,  B.C. 

In  this  mine  and  the  adjacent  Knob  Hill,  we  have  a  still 
wider  and  larger  orebody  than  at  any  point  in  the  Le  Roi.  Not 


MINE  TIMBERING 

only  is  the  deposit  of  immense  size,  but  the  grade  of  the  ore  is 
much  lower,  necessitating  a  much  lower  cost  of  extraction,  in 
order  to  mine  it  at  a  profit.  To  accomplish  this  a  large  output 
is  essential,  and  cheap  and  rapid  means  of  handling  it,  from 
breaking  the  ore  down  until  it  finally  reaches  the  smelter. 
The  ore  is  mined  in  three  ways  in  these  deposits: 

(1)  By  open  cuts, 

(2)  By  the  milling  or  "glory  hole"  method,  and 

(3)  By  the  ordinary  overhand  stoping  with  the  use  of  square 

sets. 

The  open  cut  was  on  a  level  with  the  railroad  track,  and  a 
tramway  was  built  with  an  incline  to  enable  a  small  hoist  to  bring 
the  ore  up  high  enough  to  dump  into  the  railroad  cars.  This  is 
quite  an  ordinary  method  and  needs  no  further  comment,  the 
ore  being  broken  down  in  the  usual  way.  Later,  however,  when 
a  considerable  excavation  had  been  made,  a  steam  shovel  was 
used,  which  handled  rock  of  much  larger  dimensions.  Boulders 
too  large  to  go  into  the  bucket  were  picked  up  by  means  of  a 
chain.  They  were  loaded  either  directly  into  the  shipping  cars, 
when  the  ore  was  crushed  at  the  smelter,  or  into  small  wooden 
cars,  and  taken  to  the  crusher  first  by  horses,  and  at  the  present 
time  by  a  small  locomotive.  Three  steam  shovels  are  now  at 
wrork  for  this  company  in  their  low-grade  orebodies,  and  they  will 
tend  greatly  towards  solving  the  problem  of  decreasing  the  cost, 
and,  at  the  same  time,  largely  increasing  the  shipments. 

The  milling  or  "glory  hole"  method  also  applies  more  par- 
ticularly to  the  Knob  Hill  than  to  the  Old  Ironsides  Mine.  It 
consists  essentially  in  driving  a  tunnel  into  the  deposit  to  be 
excavated,  as  low  as  can  be  conveniently  worked  without  the 
sides  caving  in,  and  then  a  raise  to  connect  with  the  surface. 
At  the  bottom  of  the  raise  a  very  substantial  chute  is  constructed 
from  which  the  ore  can  be  readily  withdrawn  into  cars.  Opera- 
tions then  begin  on  the  surface  and  the  ore  is  milled  or  broken 
down,  being  blasted  into  the  raise.  Suitable  faces  and  benches 
are  soon  established,  and  a  better  command  obtained  of  the  size 
of  the  rock  going  down  the  chute  or  raise.  Very  deep  holes  are 
drilled  and  very  heavy  blasts  set  off,  thus  breaking  the  ore  quite 
rapidly  and  economically.  The  benches  are  arranged  in  such  a 
manner  that  a  great  amount  of  the  rock  rolls  down  into  the  chute, 
which  is  always  partially  filled,  without  much  handling. 


MINE  TIMBERING 


87 


The  advantages  of  this  method  are  as  follows:  practically  no 
expense  for  timber;  no  bad  air  to  work  in  and  hence  no  time 
lost ;  few  drill  holes  needed  and  comparatively  little  powder  used ; 
the  ore  handled  mostly  by  gravity. 

The  disadvantage  is  that  there  is  a  limit  to  the  depth  at 


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FIGS.  74  AND  75.  —  LAGGING  ARRANGEMENT,  OLD  IRONSIDES  MINE. 

which  the  ore  can  be  excavated,  because  of  the  caving  or  falling 
in  of  the  sides. 

On  the  deeper  levels  of  the  mine  the  usual  method  of  under- 
ground development  was  carried  out.  The  system  of  mining  the 
ore  was  very  similar  to  that  in  vogue  in  the  Le  Roi,  which  has 
been  already  described.  The  timbers,  however,  were  stouter, 
and  the  method  of  lagging  was  different.  In  arranging  the  lagging 


88 


MINE  TIMBERING 


the  object  was  to  place  it  in  such  a  way  that  the  broken  ore  could 
be  rolled  into  the  chutes  with  the  least  possible  amount  of  shov- 
eling. To  accomplish  this,  lagging  about  10  ft.  long  was  laid  on 
the  caps,  close  together,  and,  if  the  poles  were  weak,  perhaps  a 
double  layer.  A  space  two  sets  square  had  the  poles  laid  parallel, 
and  the  adjacent  squares  were  poled  at  right  angles  to  these. 
The  caps  and  collar  braces  were  of  the  same  dimensions,  hence  it 
did  not  matter  which  way  the  lagging  was  arranged.  In  this  way 
the  poles  had  a  good  support  at  both  ends,  because  they  reached 
well  over  two  5-ft.  sets.  When  it  was  desired  to  remove  the 
muck,  all  that  was  necessary  was  to  move  a  pole  so  that  the  ore 
could  drop  through.  As  it  rolled  down,  with  the  aid  of  a  pick 
or  bar,  another  and  another  pole  could  be  rolled  from  beneath  it. 
In  this  manner  the  writer  has  rolled  into  the  chute  40  or  50  tons 
in  four  or  five  hours.  Any  very  large  boulders,  of  course,  were 
smashed  with  a  sledge  hammer.  Fig.  75  is  meant  to  show  the 
arrangement  of  the  lagging.  It  is  a  plan  of  the  floor  immediately 
under  the  ore  to  be  mined,  while  Fig.  74  is  an  elevation  of  the  same. 


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FIGS.  76  AND  77.  —  CHUTE  ARRANGEMENT,  OLD  IRONSIDES  MINE. 
A  special  method  of  chute  building  was  adopted  here.     Above 
the  first  floor  they  were  built  in  the  shape  of  a  long  trough-like 


MINE  TIMBERING  89 

V  running  from  one  brace  down  and  across  to  the  next.  Poles 
were  used  for  this  work,  and  spiked  securely  to  the  square  sets. 
Figs.  76  and  77  show  the  arrangement  of  the  chutes  in  elevation 
and  plan.  At  convenient  intervals  an  outlet  was  made,  and 
between  the  chute  gates  the  ore  was  allowed  to  pile  up  a  little. 
The  ore  was  trammed  to  the  shaft  in  ordinary  one-ton  cars,  and 
hoisted  to  the  surface  on  a  cage  through  a  vertical  shaft. 

It  will  thus  be  seen  from  this  brief  account  that  a  very  easy 
and  economical  method  of  removing  the  ore  was  in  vogue  at  the 
Old  Ironsides. 


BALTIC  MINE,  BALTIC,  MICH. 

The  method  adopted  in  the  Baltic  is  peculiar  to  this  mine, 
and  is  not  used,  as  far  as  I  am  aware,  at  any  other  mine 
in  the  copper  country.  It  is  a  simple  system  of  walling  up  each 
tramway  with  waste  rock,  thereby  keeping  a  roadway  open,  and 
filling  in  above  with  the  gangue  and  country  rock,  as  convenient. 
In  this  way  the  expense  of  putting  in  timber  is  minimized,  which 
is  offset  by  the  walling  and  filling.  The  method  is  only  appli- 
cable when  the  vein  carries  waste,  or  when  waste  rock  is  easily 
and  cheaply  obtainable. 

The  material  mined  is  native  copper,  which  occurs  in  a  vein 
of  lava  rock  both  as  "shot  copper"  of  varying  size  scattered 
throughout  the  rock,  and  as  "mass  copper,"  which  is  solid  copper 
of  more  or  less  irregular  shape.  The  pitch  of  the  vein  is  about 
70  to  72  deg.,  and  the  width  varies  from  20  to  50  ft.  Parts  of 
the  vein  are  more  or  less  barren  of  copper,  and  this  rock,  called 
"poor  rock,"  is  picked  out  by  the  "copper  pickers,"  and  forms  a 
good  part  of  the  filling. 

The  vein  was  opened  up  by  shafts  and  drifts,  and  when  stoping 
began,  the  drifts  were  widened  out  to  the  full  width  of  the  vein. 
After  the  copper  rock  was  cleaned  out  from  the  face,  the  poor 
rock  was  taken  back  in  cars,  and  shoveled  to  one  side.  When 
the  "wallers"  had  enough  rock  to  start  on  they  began  and  walled 
it  up  on  each  side  of  the  track,  leaving  a  space  of  7  ft.  for  a  tram- 
way. The  walls  were  made  about  7  ft.  high,  and  heavy  stull 
timbers  laid  on  them  as  caps.  These  caps  were  placed  about 
3  ft.  apart  and  covered  with  cedar  lagging,  so  that  no  rock  could 
come  through.  (See  Fig.  78.) 


90 


MINE  TIMBERING 


At  intervals  of  about  40  ft.  spaces  were  left  for  chutes  on  one 
side  of  the  track.  They  were  built  up  with  rock  and  had  a  timber 
margin  for  planks  to  be  spiked  to.  In  the  bottom  of  the  chute 
flatted  hemlock  timbers  were  laid,  and  a  heavy  sheet-iron  plate 


FIG.  78.  —  METHOD  OF  WALLING  UP,  BALTIC  MINE. 

was  fastened  to  them  with  drive  bolts.  The  bottom  of  the  chute 
was  made  flat  because  very  large  boulders  were  handled  in  it. 
For  a  gate  a  spout  was  used,  one  end  of  which  was  raised  and 
lowered  by  means  of  a  long,  stout  lever.  The  copper  rock  thrown 


/w/-^////d&///& 
FIG.  70.  —  METHOD  OF  WALLING  UP,  BALTIC  MINE. 

into  the  chute  was  pulled  out  by  the  trammers  into  two-ton  cars, 
taken  to  the  shaft,  and  dumped  directly  into  the  skips. 

When  the  work  had  progressed  far  enough  on  the  station 
level,   overhead  stoping  began  above  the  caps  and  walls,   by 


MINE  TIMBERING 


91 


drilling  with  machines  and  blasting  in  the  usual  manner.  The 
rock  broken  down  was  picked  over  by  the  copper  pickers,  the 
copper  rock  being  thrown  into  the  chutes,  and  the  poor  rock 
thrown  back  to  fill  up  the  excavation.  As  more  and  more  filling 
accumulated,  the  chutes  were  carried  upward  in  the  form  of  a 
hole  5  ft.  square,  by  means  of  heavy  cribbing  flatted  at  the  ends 
and  spiked.  (See  Fig.  79.)  Sometimes  the  pickers  needed  wheel- 
barrows to  get  the  rock  into  the  chute  or  "mill." 

In  stoping,  a  good  breast  was  carried  along,  and  heavy  holes 
drilled,  since  no  damage  could  be  done  by  heavy  blasts,  though 
it  was  not  advisable  to  shatter  the  roof  too  much.  As  the  room 
grew  in  hight  the  back  got  farther  and  farther  away  from  the 
filling.  This  necessitated  the  use  of  long  posts  for  the  machines 
and  staging  for  the  miners  to  work  from.  The  idea,  of  course, 
was  to  work  as  much  as  possible  from  the  top  of  the  broken 
rock,  but  as  there  were  100  ft.  between  levels,  and  not  a  very 
high  percentage  of  poor  rock,  it  became  necessary  to  cut  out  the 
foot-  or  the  hanging  wall  to  fill  in,  and  thus  reach  the  back.  This 
should  always  be  done  after  the  copper  rock  has  been  picked  out, 
as  otherwise  much  poor  rock  would  be  mixed  with  it.  An 
attempt  is  made  to  convey  an  idea  of  the  stope  in  Fig.  80. 


FIG.  80.  —  LONGITUDINAL  SECTION  OF  STOPE,  BALTIC  MINE! 

This  method  is  supposed  to  take  out  practically  all  the  ore, 
and  the  only  use  made  of  timber  is  to  crib  the  chutes,  and  cover 
the  tracks.  The  vein  rock  is  quite  tough,  and,  with  a  slight 
arch  in  the  middle  of  the  roof,  there  is  comparatively  little  danger 
from  overhead.  The  greatest  difficulty  to  be  encountered  will 
be  in  making  connections  between  levels.  Here  the  filling  from 


92 


MINE  TIMBERING 


the  level  above  will  run  down  and  mix  with  the  copper  rock 
below.  Taken  altogether,  however,  this  is  an  excellent  method 
of  mining,  and  has  given  the  Baltic  people  satisfaction  up  to  the 
present  time. 

ATLANTIC  MINE,  ATLANTIC,  MICH. 

The  Atlantic  vein  is  similar  to  the  Baltic,  though  it  only 
averages  about  15  ft.  in  width,  and  it  does  not  carry  so  much 
copper.  This  rock  is  not  picked  over,  but  the  total  product 


Elevation  Perpendicular  to  vein 
Atlantic  Mine.  Mich. 


FIG.  81.  —  STULL  TIMBERING,  ATLANTIC  MINE. 

mined  goes  to  the  stamp  mill.  Thus  no  filling  can  be  obtained 
from  the  rock  broken  and,  the  vein  being  narrow,  stulls  can  be 
used. 

When  the  levels  have  been  opened  up  the  miners  take  con- 
tracts to  stope  out  the  pay  rock.  Each  contract  includes  a  part 
of  the  vein  99  ft.  in  length  and  extending  between  levels,  which 
are  about  85  or  90  ft.  apart,  and  the  price  is  paid  on  a  basis  of 
at  least  a  width  of  15  ft.  The  contractors  first  run  a  drift  to  the 
end  of  their  ground  and  commence  stoping,  taking  out  enough 
rock  to  put  in  the  stulls  to  protect  the  level  for  tramming. 

These  stulls  are  very  heavy,  about  20  ft.  or  more  long,  and 
placed  in  hitches  cut  in  the  walls.  They  are  inclined  at  an  angle 


MINE  TIMBERING  93 

of  about  70  deg.  to  the  horizontal,  thereby  leaving  room  for  a 
track  between  the  stulls  and  the  hanging  walls.  (See  Fig.  81.) 
At  the  same  time  they  were  quite  steep  to  prevent  them  taking 
up  more  weight  than  they  could  safely  bear.  They  are  covered 
with  lagging,  which  prevents  the  muck  from  coming  down  on 
the  track.  When  this  line  of  stulls  is  finished,  stoping  is  com- 
menced higher  on  the  vein.  The  miners  keep  rigging  up  on  the 
rock  they  break  and  it  is  trammed  out  from  below  when  they 
are  crowded  for  head  room.  In  this  way  they  are  always  close 
to  the  back,  and  work  to  the  best  advantage.  They  work  up  to 
within  15  ft.  of  the  level  above,  and  then,  as  the  rock  is  withdrawn, 
the  timbermen  place  stulls  wherever  they  are  needed  to  support 
the  hanging,  and  make  it  safe  for  the  muckers  below.  The  pillars 
left  constitute  the  floor  of  each  level. 

This  method  furnishes  one  of  the  cheapest  and  best  methods 
of  getting  out  stamp  rock  in  the  copper  country.  The  width  of 
the  vein,  its  regularity  and  pitch  or  dip,  make  this  a  peculiarly 
valuable  method  to  the  Atlantic  Company.  Without  it  the  mine 
would  probably  be  operated  at  a  loss,  as  the  copper  values  do 
not  exceed  25  Ib.  per  ton  of  rock. 

Coming  now  to  the  iron  country  of  Michigan  we  find  a  some- 
what different  order  of  things.  Here  we  do  not  have  the  ores  in 
regular  well-defined  veins,  as  is  the  case  in  the  copper  country. 
On  the  contrary,  the  ore  occurs  in  blankets  or  deposits  of  more 
or  less  irregular  shape,  and  the  sustaining  power  of  the  adjacent 
rock  is  a  far  more  uncertain  quantity.  The  ore  itself  varies  a 
great  deal,  some  being  soft  and  capable  of  caving,  while  much  is 
hard,  and  a  caving  system  could  not  be  adopted.  Some  again 
is  intermediate  between  hard  and  soft  ore,  and  a  combination  of 
a  caving  system  with  some  other  method  becomes  a  necessity. 

BARNUM  MINE,  ISHPEMING,  MICH. 

This  is  a  hard  ore  mine  producing  a  hard  hematite.  The 
system  of  mining  is  simple  and  inexpensive,  although  about 
one-third  of  the  ore  is  left  for  pillars.  The  levels  are  from  40  to 
50  ft.  apart,  and  after  being  driven,  raises  are  run  up  to  the 
level  above  at  convenient  intervals.  When  the  raises  are  com- 
pleted, the  miners  begin  at  the  top  and  mill  the  ore  down  the 
raise  in  a  manner  similar  to  the  "glory-hole"  method  already 


94 


MINE  TIMBERING 


described,  except  that  the  work  is,  of  course,  underground.  They 
work  from  convenient  benches  and  gradually  cut  out  large  cham- 
bers. Care  must  be  exercised  in  scaling  any  loose  rock  from  the 
roof  while  the  men  are  close  to  it,  because  when  they  get  lower 
down  the  roof  will  be  out  of  reach.  Wherever  necessary,  pillars 
are  left  22  ft.  square,  one  being  as  nearly  as  possible  directly 
above  the  one  below.  Machines  and  tripods  are  employed,  and 
the  rate  of  drilling  is  slow,  varying  from  4  ft.  to  15  ft.  of  hole 
per  shift.  The  ore  is  also  hard  to  break,  and  a  50-per  cent, 
dynamite  is  used.  There  are  no  pockets  in  the  mine,  and  the 
cars  are  hoisted  to  the  surface  by  a  single-compartment  shaft. 
As  the  method  at  the  Barnum  is  so  simple,  little  more  need  be 
said;  suffice  it  to  say  that  the  method  is  very  wasteful  of  ore, 
because  such  a  large  percentage  of  it  is  left  in  the  mine. 

Level 


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FIG.  82.  —  STOPES  AND  PILLARS. 

SECTION  16  MINE,  ISHPEMING,  MICH. 

The  ore  from  this  mine  was  also  fairly  hard  and  a  similar 
method  of  mining  was  adopted.  Levels  were  run  from  the  shaft 
to  the  orebody  at  intervals  of  about  60  ft.,  and  a  drift  run  along 
the  foot-  or  hanging  wall  as  desired.  From  this  drift  raises  were 
driven  every  50  ft.  to  the  level  above,  thus  making  a  passage  for 
timber  and  ore.  At  15  ft.  below  the  upper  level  the  raise  was 
enlarged  into  a  stope  or  room,  and  made  of  such  a  size  that  it 
would  be  safe  to  work  in,  dividing  pillars  being  left  on  each  side. 
The  ore  was  thus  removed  down  to  the  level  below,  and  pillars 
were  left  extending  across  the  orebody. 

When  the  rooms  had  all  been  excavated  in  this  manner  the 
robbing  of  the  pillars  began.  The  pillars  were  usually  25  ft. 
through,  and  they  were  undercut  on  one  side  to  a  distance  of 


MINE  TIMBERING 


95 


about  9  ft.,  and  right  across  the  vein.  The  timbermen  then 
built  cribs  of  timber  8  ft.  square  in  this  space,  and  as  many  as 
they  had  room  for,  leaving  a  space  of  3  ft.  between  them  for  a 
passage.  These  cribs  were  built  right  up  to  the  back,  wedged 
down  and  filled  with  rock.  (See  Fig.  83.) 


Robbing  and  Filling 


Tramway  Set 

FIG.  83.  —  FILLING  SYSTEM,  SECTION  16  MINE. 

The  next  step  was  to  undercut  another  9  ft.  and  treat  it  with 
timber  cribs  and  rock  in  a  precisely  similar  manner.  Finally  the 
last  portion  of  the  pillar  was  removed  and  cribbed,  and  the  pillar 
rested  now  entirely  on  the  crib  supports.  The  stopes  on  either 
side  of  the  pillar  were  then  filled  with  loose  rock  to  the  level  of  the 
top  of  the  cribs,  and  also  in  between  them,  a  passageway,  of 
course,  being  left  for  tramming. 

The  pillar  having  been  undercut  to  a  hight  of  about  8  ft., 
another  slice  is  removed  in  much  the  same  manner,  at  a  higher 
level.  Mills  become  a  necessity  in  order  to  let  the  ore  down 
through  the  rock  filling,  and  these  are  made  of  round  poles  and 
placed  at  convenient  intervals.  As  the  pillar  is  attacked  at  a 


96  MINE  TIMBERING 

higher  point  the  work  proceeds  on  the  top  of  the  filling,  hence 
by  this  method  it  is  possible  to  remove  practically  all  the  ore. 

The  filling  used  is  obtained  from  two  sources :  part  is  furnished 
by  the  ordinary  development  work,  and  the  remainder  is  ob- 
tained from  the  dump  of  a  neighboring  mine.  It  is  loaded  into 
railroad  cars,  and  dumped  directly  down  a  raise  for  that  purpose. 
This  raise  is  tapped  where  desired  by  a  rough  chute,  and  the  rock 
trammed  in  small  dump  cars  running  on  tracks  laid  on  the  filling. 
These  tracks  are  readily  moved  laterally,  so  that  the  rock  is 
conveyed  to  the  place  desired  without  very  much  shoveling  being 
required. 

In  parts  of  the  mine  where  the  orebody  is  of  such  nature  that 
ore  pillars  are  not  necessary,  a  method  of  overhand  stoping  is 
prosecuted.  This  operation  is  followed  directly  by  the  filling, 
the  ore  being  mined  out  and  the  excavation  filled  with  waste 
rock.  Where  the  roof  is  not  good,  cribs  are  built  on  the  filling  to 
support  it. 

Again,  in  other  parts  of  the  mine,  filling  is  not  used,  but  the 
ore  is  mined  from  each  level  upwards,  and  the  regular  square-set 
timber  erected. 

The  methods  of  mining  at  this  mine  are  therefore  somewhat 
special  and  varied.  The  cause  of  this  variation  is  due  to  the 
fact  that  the  orebody  changes  from  place  to  place  in  hardness, 
width,  and  accessibility..  In  some  parts  of  the  mine  it  is  hard 
to  introduce  the  filling,  while  in  others  it  is  a  cheap  and  efficient 
adjunct  in  extracting  the  ore.  Wherever  used  it  forms  a  com- 
pact and  satisfactory  substitute  for  timber,  which,  to  perform 
the  same  duty,  would  be  quite  expensive. 


SOFT  ORE  HEMATITE  MINE,  ISHPEMING,  MICH. 

Here  we  have  a  mine  which  was  formerly  covered  by  Lake 
Angeline,  a  body  of  water  of  about  100  acres  in  extent,  and 
50  ft.  deep  in  the  deepest  part.  The  water  was  pumped  out  by 
means  of  powerful  pumps,  and  the  lake  bed  became  compara- 
tively dry.  On  the  margin  of  the  old  lake  shafts  were  sunk, 
and  the  mining  of  the  large  deposits  of  soft  ore  was  begun.  The 
ore,  being  a  soft  red  hematite,  was  very  easy  to  break  down,  but  it 
was  impossible  to  have  large  chambers  excavated,  because  of  its 


MINE  TIMBERING 


97 


heavy  settling  nature.     As  the  soft  ore  caved  so  readily,  a  caving 
system  of  mining  was  soon  inaugurated. 

Haulage  ways  were,  as  far  as  possible,  made  in  solid  rock. 
Then  raises  were  driven  to  the  top  of  the  ore  deposit,  at  intervals 
of  from  60  to  100  ft.,  and  cribbed  with  two  compartments,  one 
for  a  ladder  road  and  the  other  for  ore.  Sub-levels  were  also 
made  to  facilitate  operations.  The  ore  was  loaded  into  cars 
holding  about  2J  tons,  which  were  attached  to  a  "bull-dog,"  and 
taken  to  the  shaft  in  trains  of  six  or  seven.  The  bull-dog  was 


.^^^^^^^Sa^^&^^^  ^"".  Qi:i:^::^.\^;:v':ff^^^^^ 


Top  Slicing 


FIG.  84.  —  CAVING  SYSTEM,  SOFT  ORE  HEMATITE  MINE. 

operated  by  a  cable,  each  end  of  which  passed  around  a  drum 
run  by  compressed  air.  One  engine  was  located  at  the  shaft 
and  the  other  at  the  end  of  the  haulage  way.  At  the  shaft  the 
cars  dumped  directly  into  the  skip,  and  were  moved  up  to,  and 
away  from,  the  shaft  by  hand.  The  idea  of  the  bull-dog  is  to 
facilitate  coupling,  the  cars  being  connected  to  the  bull-dog 
instead  of  directly  to  the  cable. 

When  the  chutes  were  completed  a  "top-slicing"  scheme  was 
begun.  A  drift  8x8  ft.  was  driven  parallel  with  the  deposit,  and 
timbered  with  square  sets.  Theso  sets  consisted  of  legs  and  caps 


98  MINE  TIMBERING 

as  shown  in  Fig.  84,  and  were  placed  4  ft.  apart.  At  the  raise  it 
was  important  to  have  rather  stout  timber,  because  here  the  tim- 
ber was  expected  to  stand  the  longest,  and  was  therefore  sub- 
jected to  most  pressure.  Farther  from  the  raise  or  chute  the 
timber  was  much  smaller,  6  to  12  in.,  and  the  caps  were  covered 
with  light  lagging.  The  caps,  as  a  rule,  were  a  few  inches  larger 
in  diameter  than  the  legs. 

The  second  step  in  top-slicing  is  to  begin  at  the  farthest  end 
of  the  drift  and  cross-cut  to  both  foot-  and  hanging  walls.  These 
drifts  are  also  8x8  ft.  and  are  driven  parallel,  and  one  after 
another,  until  the  whole  area  is  excavated,  that  around  the 
chute  being  taken  out  last.  The  same  procedure  is  followed  on 
the  opposite  side  of  the  chute.  The  floor  is  then  all  lagged  over 
to  prevent  mud,  gravel,  etc.,  from  mixing  with  the  ore  when 
subsidence  takes  place.  The  legs  of  the  sets  are  blasted  out  and 
the  overlying  burden  is  lowered,  as  a  consequence,  all  over  the 
area  in  question. 

Mining  below  this  is  now  done  by  the  real  caving  system. 
The  miners  drop  down  12  or  15  ft.,  depending  on  the  hardness 
of  the  ore,  and  run  a  drift  as  before.  Side  rooms  are  run  to 
foot-  and  hanging  walls,  and  when  these  are  reached  the  most 
remote  sets  are  blasted,  and  the  roof  is  caved  in.  By  working  as 
they  retreat  practically  all  the  ore  is  removed  from  beneath  the 
lagging  above,  only  one  set  usually  being  blasted  at  a  time. 
Sometimes  several  rooms  are  worked  out  before  caving,  but  it  is 
unsafe  to  leave  them  for  any  length  of  time.  It  is  deemed  ad- 
visable to  finish  one  room  before  beginning  another.  In  this 
manner  a  whole  slice  is  taken  out,  and  overlying  debris  or  "  gob  " 
is  lowered  once  more.  Then  a  drop  is  made  for  another  and 
another  slice,  until  the  bottom  of  the  deposit  is  reached. 

Contrary  to  what  might  be  expected  this  is  a  comparatively 
safe  method  of  mining.  The  men  work  near  the  back  all  the  time, 
and,  should  there  be  any  danger,  warning  is  given  by  the  gradual 
crushing  of  the  timber.  No  large  rooms  are  excavated  at  any 
one  time,  and  there  is  practically  no  danger  from  this  source. 

The  system  is  also  cheap,  comparatively  little  timber  is  used, 
and  even  that  is  of  an  inferior  order.  Very  little  powder  is  neces- 
sary, and  there  is  not  much  drilling  done.  Holes  are  drilled  with 
machines,  augurs,  or  hammer  and  drill,  as  the  particular  hardness 
of  the  ore  may  make  advisable.  The  cost  of  mining  is  low,  and 


MINE  TIMBERING  99 

contracts  run  at  $4.50  for  an  8x8-ft.  drift  per  foot  of  advance. 
The  miners  make  from  $55  to  $60  per  month  after  deducting  all 
expenses  for  powder,  caps,  fuse  and  candles. 

QUEEN  MINE,  NEGAUNEE,  MICH. 

In  the  Queen  mine,  as  its  name  implies,  we  have  a  fine  example 
of  systematic  iron  mining.  The  orebody  is  large  and  fairly  regular 
and  lends  itself  particularly  well  to  methodical  development.  The 
ore  is  not  very  hard,  and  it  is  not  soft  enough  to  cave,  as  in  the 
Hematite.  A  special  method  has  been  adopted  and  seems  to 
answer  the  purpose  very  well.  The  system  in  vogue  starts  out  as 
a  square-set  system  and  develops  a  caving  system  as  the  wrork 
proceeds. 

The  orebody  is  in  the  shape  of  a  lens,  and  dips  to  the  north 
at  an  angle  of  38  deg.,  and  also  pitches  to  the  west  at  45  deg. 
Six  shafts  have  been  sunk,  the  first  three  on  the  eastern  side 
being  now  worked  out.  From  the  shaft  a  well  laid  out  system 
of  haulage  ways  has  been  driven,  special  attention  being  given 
to  prevent  interference  of  cars  with  timber,  and  vice  versa.  The 
timber  can  be  handled  on  one  line  of  tracks  often  at  right  angles 
to  the  haulage  tunnels.  The  main  ore  drift  has  been  double 
tracked,  and  an  endless  cable  picks  up  the  loaded  cars  of  ore  as 
desired,  and  takes  them  to  the  shaft.  The  cable  is  operated  by 
an  engine  at  the  shaft  with  a  special  device  to  keep  up  uniform 
tension.  The  cars  are  attached  to  the  cable,  which  is  always 
moving,  by  hand,  and  are  detached  automatically  when  they 
reach  the  shaft.  They  are  dumped  into  pockets  and  sent  back 
by  the  cable  on  the  other  track.  The  expense  of  operating  this 
haulage  system  is  only  J  cent  per  ton. 

Coming  now  to  the  mining  system  proper,  we  find  a  face  of 
3  sets  wide  or  25  ft.  carried  forward,  and  timbered  with  good 
substantial  square-set  timber.  Then  parallel  to  this  another  sim- 
ilar face  is  driven,  but  with  a  pillar  5  sets,  or  40  ft.,  left  between. 
Cross-cuts  are  also  run,  blocking  out  the  pillars  into  squares. 
(For  elevation  and  plan  of  stopes  and  pillars  see  Figs.  85  and  86.) 
At  the  same  time  these  faces  are  being  worked  on  the  level, 
another  and  another  slice  is  stoped  out  and  timbered  above.  In 
this  way  the  orebody  is  honeycombed  to  the  top  of  the  deposit, 
pillars  and  rooms  alternating  throughout  the  level. 


100 


MINE   TIMBERING 


After  the  ore  has  been  excavated  in  this  manner  .the  work  of 
taking  out  the  pillars  and  caving  begins.  A  raise  8x8  ft.  is 
now  run  up  through  the  center  of  the  pillar,  and  timbered  with 
the  usual  sets.  Thus  between  the  center  set  and  the  timber 
in  the  rooms  outside  there  is  a  distance  of  two  sets.  The  top  of 
the  pillar  is  taken  out  to  the  depth  of  one  set,  and  caps  of  double 
length  are  used  to  connect  the  center  with  the  outside  sets.  This 






<fS*//S  ^'// 

£             // 

*?w^ 

Pillar 

Removed 

R 

LI 

u 

\   I 

u 

u 

u 

\   1 

— 

\ 

Vertical  Section  through  A-B 


Plan  of  Stope,  Queen  Mine. 
Negaunee,  Mich. 

FIGS.  85  AND  86.  —  STOPES  AND  PILLARS,  QUEEN  MINE. 

is  done  on  the  four  sides,  and  the  top  heavily  lagged.  The  ore 
is  then  worked  downward,  using  the  long  caps  at  each  step,  but 
without  lagging.  The  material  of  the  pillar  is  readily  broken  up 
and  sent  down  the  chutes  in  the  outside  sets;  in  fact,  it  is  the 
most  rapid  method  of  breaking  ore  in  the  mine. 

When  the  pillars  have  all  been  robbed  the  tracks  are  taken 


MINE  TIMBERING  101 

up,  a  flooring  of  poles  is  laid,  except  where  there  is  a  rock  floor, 
and  every  second  leg  is  blasted  out,  thus  bringing  down  the  whole 
mass  of  timbers  as  well  as  the  roof. 

A  system  called  "scramming"  is  used  to  mine  on  the  level 
below.  The  level  is  divided  into  50-ft.  squares,  and  in  each  a 
raise  4x9  ft.,  in  two  compartments,  is  run  up  to  the  lagging 
above,  the  levels  being  85  ft.  apart.  Starting  9  ft.  down,  a  drift 
is  driven  from  the  raise  25  ft.  each  way,  and  timbered  with  light 
sets.  The  ore  is  shoveled  directly  into  the  chute  or  a  wheel- 
barrow is  used.  A  second  drift  is  run  beside  the  first,  though 
not  always,  and  the  bottom  is  lagged  over.  Then  the  legs  are 
blasted,  and  the  overlying  debris  caved,  as  in  the  Hematite  mine. 
The  process  is  repeated  until  the  2500  sq.  ft.  is  lowered  9  ft. 
The  miners  now  drop  once  more,  and  repeat  the  operation,  and 
so  work  down  to  the  level. 

While  work  is  progressing  in  the  drift  the  timbers  begin  to 
crack,  which  is  a  good  sign,  because  it  shows  that  the  mass  above 
is  slowly  settling.  If  the  timbers  do  not  show  that  they  are 
supporting  great  weight  the  debris  has  become  "hung  up,"  and 
is  liable  to  come  down  at  any  moment.  Seeing  this  the  miners 
either  blast  it  down,  or  get  out  of  the  place.  When  the  timbers 
show  pressure  the  workmen  are  safe,  as  the  mingled  rock  and 
timbers  settle  very  slowly,  an  inch  or  so  a  day. 

This  method  of  scramming  is  also  used  in  new  workings,  under 
gravel,  sand,  or  loose  rock.  In  that  case  great  pits  are  formed  on 
the  surface  immediately  above. 

In  the  foregoing  description  of  these  several  mining  methods, 
little  attempt  has  been  made  to  go  into  the  minute  details  of  the 
various  schemes  presented.  The  systems  taken  up  represent  the 
actual  practice,  in  their  most  essential  features,  of  underground 
work  in  western  America,  outside  of  coal  mining.  Much  more 
might  be  said  in  regard  to  many  matters  connected  with  them, 
such  as  their  comparative  expense,  the  percentage  of  ore  recov- 
ered, their  suitability  to  general  conditions,  etc.  To  go  farther 
into  these  matters  would  make  the  paper  unduly  long.  No 
references  have  been  consulted,  as  I  have  gathered  all  the  data 
at  first  hand. 

During  the  discussion  of  his  paper  Mr.  Parlee  said  that  in 
connecting  up  timber  between  levels,  it  was  considered  good 


102  MINE  TIMBERING 

practice  to  have  sills  of  the  level  below,  in  the  sme  vertical 
plane  with  those  above,  surveyed  and  laid  down  accordingly, 
but  in  carrying  up  the  sets  100  ft.  it  was  almost  impossible  to 
go  up  straight  enough  to  have  post  match  with  post  properly. 
They  would  come  either  one  side  or  the  other  of  the  vertical 
plane  and  be  out -of  plumb  perhaps  a  foot  or  two.  Unless  they 
could  meet  the  upper  sets  exactly,  it  did  not  really  matter  whether 
the  sills  below  were  surveyed  or  not,  except  to  get  the  general 
direction  of  the  timber.  The  sills  of  the  upper  level  were  caught 
up  by  the  cross  timbers,  reaching  two  or  three  sills.  Little 
attempt  was  made  to  have  posts  of  lower  sets  directly  under 
posts  of  upper  sets.  Bulkheads  were  often  used  and  the  rock 
must  be  blasted  out  carefully  and  not  too  fast. 

Mr.  Parlee  also  said  that  the  square-set  system  was  used 
wherever  the  ore  was  too  hard  to  cave  without  it.  It  was  not 
the  intention  in  the  paper  to  discuss  all  the  methods  used  in 
each  mine,  but  only  those  especially  valuable.  Different  methods 
might  be  used  under  different  conditions. 

The  chairman  remarked  that  what  Mr.  Parlee  had  said  about 
the  impracticability  of  exactly  connecting  the  timbering  of  ad- 
joining levels  held  true  in  all  parts  of  the  mining  world.  The 
theory  was  that  posts  in  successive  levels  should  come  under  one 
another,  and  in  certain  mines  that  he  had  visited  more  or  less 
successful  attempts  had  been  made  to  do  this,  but  in  most  cases 
the  method  described  by  Mr.  Parlee  had  to  be  adopted.  As 
he  had  said,  the  main  thing  was  to  see  that  the  vertical 
lines  were  kept  true  and  that  the  timber  was  put  in  substantially. 
Sometimes  comparatively  heavy  bulkheads  were  used.  It  was, 
of  course,  possible  to  survey  with  sufficient  accuracy  to  have  the 
posts  placed  perfectly  plumb  and  in  line,  but  this  was  too  trouble- 
some, and  it  was  still  more  troublesome  to  erect  great  masses  of 
sets  exactly  in  line  and  plumb,  especially  when,  as  was  frequently 
the  case,  there  was  movement  going  on  in  the  orebody  or  hanging 
wall. 


MINE    TIMBERING 

IN    SECTION    16    OF    THE    LAKE    SUPERIOR    MINING 
COMPANY,    MICHIGAN 
BY  C.   ST.   G.   CAMPBELL 


MINE  TIMBERING   IN   SECTION   16   OF  THE   LAKE 
SUPERIOR  MINING   COMPANY,   MICHIGAN1 

BY  C.  ST.  G.  CAMPBELL 

IN  the  following  paper  it  will  be  necessary  to  depart  some- 
what from  the  subject  proper  and  give  a  brief  description  of  the 
location  of  the  mine,  the  method  of  mining  the  ore,  the  manage- 
ment, etc. 

Section  16  is  essentially  a  hard  ore  iron  mine,  situated  three- 
quarters  of  a  mile  from  Ishpeming,  a  town  fifteen  miles  from 
Marquette,  on  the  south  shore  of  Lake  Superior. 

The  mine  is  worked  chiefly  for  hard  ore,  there  being  three 
large  lenses,  each  of  a  different  grade,  according  to  the  percent- 
ages of  iron  and  phosphorus  contained.  There  are  also  two 
"pockets"  of  soft  ore,  which  is  locally  known  as  "hematite,"  but 
after  mining  these  pockets  for  some  time,  it  was  found  that  the 
ore  was  too  high  in  phosphorus  to  compete  with  the  soft  ores  of 
the  surrounding  mines.  So,  for  the  present,  at  least,  the  mining 
of  it  has  ceased. 

The  hard  ore  is  found  with  a  foot-wall  of  decomposed  diorite, 
resembling  soapstone,  and  a  hanging  wall  of  quartzite  or  jasper. 
A  great  dike  of  diorite  cuts  across  the  deposit  and  makes  the 
formation  somewhat  irregular.  The  three  lenses  dip  at  an  aver- 
age of  70  deg.  with  the  horizontal.  They  have  an  east  to  west 
strike  and  vary  very  much  in  their  dimensions,  ranging  from 
10  to  700  ft.'  long.  The  dimensions  of  the  so-called  "south 
vein"  have  not  yet  been  determined,  as  it  reaches  below  present 
operations. 

The  method  of  extracting  this  hard  ore  is  as  follows:  At 
intervals  of  60  ft.,  levels  are  run  out  from  the  vertical  or  hoisting 
shaft  until  the  ore  is  reached.  A  tunnel  is  cut  along  the  length 
of  the  lens,  clinging  to  either  hanging  wall  or  foot-wall  as  the 

1  From  Transactions  oj  Canadian  Society  of  Civil  Engineers,  Vol.  18,  1903. 

105 


106 


MINE  TIMBERING 


case  may  be.  Raises  are  then  made  every  50  ft.  to  the  above 
level,  or  nearly  so,  a  back  of  15  ft.  being  left  to  make  tramming 
safe.  Through  this  back  a  small  hole  is  cut  to  let  down  timber, 
also  for  the  purposes  of  ventilation,  etc.  When  first  cut,  these 
raises  are  9  ft.  in  diameter  and  are  afterwards  widened  until 
the  dividing  pillar  is  as  thin  as  is  consistent  with  safety,  say  15  ft. 
in  the  average. 

The  next  step  is,  in  many  ways,  modified  by  the  width  of  the 
lens,  but  it  suffices  to  say  that  the  stope  is  carried  across  the 


Plans  of  2nd  and  io1:h  Levels  to  Left 
and  Right  of  Hoisting  Shaft  Respectively. 


Tha  three  lines  represent  the  location  of  thr 
vertical.sections  through  the  deposit. 


Shaft  No.  1 
(Inclined) 

Boundary  of  Pittsburg  and  Lake  Angdine  Mine  1 

FIG.  87.  —  SECTION  16  MINE. 
Projection  of  2d  and  10th  levels.     The  levels  are  370  ft.  apart. 

width  of  the  vein,  the  shift  boss  using  his  own  discretion  as  to 
the  method  employed.  Finally,  however,  the  stopes  or  raises 
are  filled  up  with  rock,  leaving  a  timber  tunnel  for  the  passage  of 
trams  on  the  level  below.  Mills  are  also  built  and  rock  filled  in 
around  them,  a  process  which  will  be  described  more  fully  later. 
The  pillars  are  then  mined  out  and  their  places  filled  in  with 
rock.  In  this  way  all  the  ore  is  secured. 

The  hematite,  so  called,  is  mined  by  the  "  square-set "  system, 
which  consists  of  taking  out  slice  after  slice  of  the  ore,  the  length 
and  breadth  of  the  pocket,  and  in  its  place  putting  timber  in  the 


MINE  TIMBERING  107 

form  of  skeleton  cubes,  the  sides  of  which  measure  8  ft. 
These  cubes  or  square  sets,  as  they  are  called,  are  put  in  one  at 
a  time,  just  enough  ore  being  taken  out  to  allow  the  erection  of 
a  single  square  set.  The  pocket  is  worked  from  bottom  upward, 
thus  securing  the  advantage  of  gravity  for  the  removal  of  the 
ore.  All  the  ore  is  sent  down  by  means  of  improvised  chutes 
made  of  lagging. 

The  mine  is  at  present  850  ft.  deep  and  the  shaft  is  still  being 
sunk  to  tap  the  south  vein.  There  are  at  present  13  levels, 
12  of  which  open  on  to  the  shaft.  The  4th,  5th,  6th,  7th  and 
8th  levels  have  all  been  mined  out  even  to  the  pillars.  On  the 
lower  levels,  tunneling  and  raising  are  being  carried  on,  while  on 
the  first  three  levels  the  "robbing  of  the  pillars"  is  not  yet 
completed. 

There  are  two  other  shafts,  besides  the  one  above  mentioned. 
These  are  used  for  ventilation  and  shooting  down  the  rock  used 
for  filling.  These  shafts,  one  of  which  is  inclined,  reach  only  to 
the  second  level.  From  there  on,  the  rock  is  sent  to  the  lower 
levels  by  means  of  mills. 

For  the  most  part,  the  "hard  ore"  justifies  its  name  and  is 
hard  and  compact,  but  occasionally  it  is  of  a  slaty  structure  or 
full  of  cracks  and  fissures.  In  such  places  it  is  necessary  to  use 
drift  sets.  Similar  protection  is  also  necessary  when  drifting 
through  decomposed  diorite,  locally  known  as  "soapstone." 

The  proposition  which  the  timberman  has  to  handle  now 
having  been  outlined,  the  respective  applications  of  the  different 
methods  will  be  taken  up  in  detail. 

The  timber  is  obtained,  for  the  most  part,  from  lumber  camps, 
the  farthest  not  being  more  than  20  miles  from  the  mine.  This 
timber  is  taken  to  the  mine  by  rail  and  stocked  near  the  main 
shaft.  Second-class  logs  are  used,  knots  and  slight  crookedness 
not  being  objectionable.  The  logs,  cut  into  either  5J-,  8-,  10-  or 
16-ft.  lengths,  are  lowered  into  the  mine  by  means  of  chains 
attached  to  the  bottom  of  the  skip.  The  timbermen  land  them 
at  the  level  station  below  with  the  aid  of  a  rope,  ship  them  on 
to  a  tram  and  take  them  to  a  timber-dock,  where  they  remain 
until  required.  Between  the  hours  of  twelve  and  one  on  the 
day  shift  the  miners  are  on  the  surface  for  lunch,  and  advantage 
is  taken  of  this  fact  to  lower  timber.  In  consequence  the  timber- 
men  remain  below  and  take  out  timber,  thus  postponing  their 


108  MINE  TIMBERING 

lunch  for  one  hour.  Hemlock  and  white  pine  are  used  for  the 
most  part  in  the  large  timbering.  Cedar  is  used  for  lagging. 
The  captain  is  at  present  experimenting  on  hard  wood.  Squared 
timber  is  used  only  in  the  shaft  and  under  certain  special  condi- 
tions elsewhere.  In  other  places  not  only  is  timber  used  round, 
but  also  with  the  bark  on.  The  life  of  a  "  stick  "  is  very  uncer- 
tain, depending  upon  the  nature  of  the  wood,  the  stress  to  which 
it  is  subjected,  and  the  temperature,  hence  the  moisture.  On 
the  7th  and  8th  levels,  immediately  above  the  pumps,  which  are 
on  the  9th  level,  the  timber  lasts  only  five  months,  after  which 
it  is  quite  easy  to  force  the  point  of  a  candlestick  six  inches  into 
the  wood  with  the  hand.  This  is  exceptional,  however.  The 
average  life  of  timber  in  the  mine  is  said  to  be  ten  years.  The 
timber  is  often  crushed  by  the  settling  of  ground,  but  there  is 
little  danger  to  life  in  this,  owing  to  the  slowness  of  settling. 

SHAFT  TIMBERING 

The  method  of  sinking  the  hoisting  shaft  is  somewhat  similar 
to  that  of  raising  a  square  set.  A  rectangular  hole  is  stoped 
down  to  a  depth  of  10  ft.,  having  a  width  of  10  ft.  and  a  length 
of  18  ft.,  and  in  this  hole  is  set  up  a  double  square  set,  8x8x16  ft. 
This  square  set  is  suspended  from  the  one  above  by  means  of 
bolts.  It  is  then  wedged  into  place  and  lagged  between  the 
timber  and  rock.  The  shaft  is  then  sunk  another  8  ft.  and  another 
double  square  set  placed  and  bolted  to  the  bottom  of  the  former, 
and  so  the  sinking  and  timbering  proceeds.  The  timber  in  the 
square  sets  used  is  from  12  to  18  in.  in  diameter.  Every  time  an 
advance  of  three  sets  (24  ft.)  is  made,  the  small  shaft  pump  is 
lowered  the  same  distance,  so  keeping  within  the  27-ft.  practical 
pumping  limit. 

The  shaft  is  then  lined  inside  the  square  sets  with  8x8-in. 
squared  timbers,  18  ft.  long,  placed  close  to  one  another  verti- 
cally, giving  the  shaft  a  box-like  character.  In  each  set  and 
parallel  to  the  ends  of  the  shaft  are  placed  cross  pieces  to  which 
planks  are  nailed,  thus  dividing  the  shaft  into  four  compartments. 
The  center  two  are  about  twice  the  size  of  the  end  ones  and  are 
used  for  skip  roads,  while  the  end  compartments  are  used  for 
pipe,  pumps  and  ladder  ways.  (See  Fig.  88.) 

The  skips,  which  are  steel  boxes  2  ft.  6  in.  square  and  5  ft. 


MINE  TIMBERING 


109 


^\iuv\          :fe§»X\        K\\kW 


110 


MINE  TIMBERING 


high,  slide  in  runners  which  consist  of  four  8x8-in.  beams,  two 
at  each  side  of  the  skip.  These  are  placed  vertically  6  in.  apart. 

Until  lately  much  trouble  has  been  experienced  from  water  in 
the  shaft.  With  a  view  to  stopping  this  water  downpour,  troughs 
or  garlands  have  been  arranged  to  carry  the  water  into  pumps  at 
depths  of  190  and  680  ft.  This  has  proved  very  effective. 

The  rock  shafts  are  very  much  simpler  in  construction,  being 
merely  lined  with  rough  unbarked  logs  built  up  like  a  crib.  It  is 
usual  to  hoist  to  the  surface  all  rock  from  the  stopes  at  the  bottom 
of  the  mine  and  send  it  down  again  to  the  levels  where  the  pillars 
are  being  robbed.  Obviously  this  supply  of  rock  would  be  insuffi- 
cient. Hence  carloads  of  loose  rock  are  brought  from  the  No.  1 
hard  ore  mine  and  dumped  down  one  or  other  of  the  shafts  as 
required. 

DRIFT  SETS 

In  running  through  soapstone  on  the  2d,  9th  and  lower 
levels,  the  back  and  sides  of  the  tunnel  are  so  weak  that  they 


RaiK 


>%^%%^^^</^^>^ 
FIG.  89.  —  SIDE  ELEVATION  OF  DRIFT  SET,  SECTION  16  MINE. 

have  to  be  supported.     This  is  done  by  means  of  "drift  sets." 
Two  trestles,  5  ft.  apart,  each  consisting  of  two  legs  and  a  cap, 


MINE  TIMBERING 


111 


with  a  covering  of  poles  resting  on  the  caps,  constitute  for  the 
main  part  what  is  known  as  the  "drift  set."  The  caps  are 
chopped  flat  at  the  ends  so  as  to  set  firmly  on  the  legs.  The 
pairs  of  legs  are  kept  apart  by  studdles,  which  are  poles  4  ft. 
6  in.  long  and  4  in.  in  diameter,  set  close  under  the  caps  and  at 
right  angles  to  them.  (See  Fig.  89.)  The  legs  are  firmly  spragged 
against  the  wall,  and  spaces  between  the  legs  lagged  on  the  rock 
side.  The  lagging  is  nailed  to  the  legs  horizontally,  one  above 
the  other,  and  the  loose  rock  is  piled  in  behind  the  partition  so 
formed.  The  covering  poles  used  are  from  4  to  5  in.  in  diameter. 
These  are  laid  lengthways,  the  ends  of  the  poles  in  one  direction 
of  a  set  resting  on  a  cap,  and  in  the  other  direction  resting  on 
the  ends  of  the  poles  of  the  preceding  set.  By  means  of  small 
pieces  of  timber  the  back  is  caught  up  and  wedged  tightly.  (See 
Fig.  90.)  If  the  pressure  is  likely  to  be  great,  owing  to  caving  in 


V 


FIG.  90.  —  END  VIEW  OF  DRIFT  SET,  SECTION  16  MINE. 

of  the  sides  of  the  tunnel,  the  legs  are  set  wider  apart  at  the 
bottom  to  ensure  greater  stability.  At  each  end  of  a  line  of 
drift  sets  slanting  props  or  "rakers"  are  propped  against  the 
legs  to  keep  the  whole  steady  when  the  blasts  go  off.  (See 
Fig.  91.) 


112 


MINE  TIMBERING 


A  single  square  set  consists  of  four  vertical  legs  arranged  in 
an  8-ft.  square,  each  leg  being  8  ft.  high.  The  legs  of  two  opposite 
sides  of  this  square  set  are  held  together  by  caps,  which  rest  on 


FIG.  91.  —  RAKER,  SECTION  16  MINE. 

SQUARE  SETS 

the  top  of  the  former.  The  two  other  sides  are  held  together, 
or,  better  still,  held  apart,  by  studdles,  in  this  case  8  to  10  in. 
in  diameter.  The  studdles  are  nailed  in  place  a  little  lower  than 
the  cap.  The  legs  and  caps  have  average  diameters  of  18  and 
12  in.  respectively.  The  top  of  each  set  is  covered  with  4-in. 
poles,  in  order  to  prevent  ore  from  coming  down  on  top  of  the 
miners.  The  whole  set  is  spragged  securely  when  first  built  and 
thus  remains  until  surrounded  with  other  sets.  For  the  sake  of 
strength  and  continuity,  the  same  two  sides  of  a  square  set  always 
have  the  caps.  If  the  stope  is  fairly  wide  and  high,  chutes  are 
built  in  so  that  each  one  is  fed  by  five  columns  of  sets.  Twice 
attempts  have  been  made  to  mine  the  hard  ore  by  this  system, 
but  without  success. 


STULLS 

In  raising  up  along  the  lens  the  hanging  wall  is  often  loose, 
great  masses  sometimes  breaking  off,  and,  in  consequence,  it  is 
necessary  to  prop  the  loose  ground  up  by  means  of  stulls.  (See 


MINE  TIMBERING 


113 


Fig.  92.)     A  stull  is  a  single  stick  of  timber  varying  in  size  ac- 
cording to  the  stress  to  which  it  is  subjected.     The  distance  is 


FIG.  92.  —  STULLS,  SECTION  16  MINE. 

measured  from  foot-wall  to  hanging  wall  and  the  stull  cut  a  cor- 
responding length.  A  socket  is  made  for  the  end  of  the  stull  on 
the  foot-wall  by  scooping  out  a  shallow  hole.  The  stull  is  then 
driven  into  place  and  fixed  tightly  by  means  of  wedges.  For 
obvious  reasons,  every  endeavor  is  made  to  have  the  greatest 
stress  along  the  line  of  the  prop,  though  in  some  cases  this  is  not 
at  all  possible.  (See  Fig.  93.) 


FIG.  93.  —  STULL,  SECTION  16  MINE. 

In  the  raises  on  the  13th  level,  it  is  impossible  to  set  up  ma- 
chines, owing  to  the  narrowness  of  the  lens  and  the  steepness 
of  the  dip,  except  as  follows:  Two  stulls  are  erected  within  7  ft. 
of  the  breast  on  either  side  of  the  raise  (8  ft.  apart).  On  the  top 
side,  poles  are  laid  halfway  up  to  the  hanging  and  then  ore  is 
pulled  down  behind  these  poles  until  a  horizontal  surface  is 


114  MINE  TIMBERING 

obtained.  On  this  surface,  which  is  about  6  ft.  wide  by  9  ft.  long, 
the  machine  is  set  up.  (See  Fig.  94.)  This  is  called  a  bench, 
and  is  used  for  16  ft.  of  advance  st oping,  after  which  another  one 
is  built  above  it  in  the  same  manner.  It  is  found  expedient  to 
remove  the  lower  ones  as  soon  as  the  top  ones  are  built,  to  give 
free  passage  for  ore. 


FIG.  94.  —  METHOD  OF  SETTING  UP  MACHINES. 

Great  difficulty  is  experienced  in  getting  timber  up  into  the 
raises.  Owing  to  oversight,  all  the  tackles  are  too  short,  so  the 
logs  have  to  be  carried  up  the  slope  by  the  timbermen,  who  hold 
the  log  under  one  arm  and  use  the  other  to  pull  themselves  up. 
It  is  quite  customary  to  do  this  for  30  ft.  before  the  tackle  comes 
into  play. 

TIMBEE  PILLARS,  OB  CRIBS 

The  duty  of  a  timber  pillar  is  to  hold  up  ground.  It  serves 
the  same  purpose  as  a  vertical  stull,  only  on  a  much  larger  scale. 
The  pillar  is  made  of  rough  unbarked  logs,  8  ft.  in  length  and 
anything  from  6  in.  to  2  .ft.  in  diameter,  according  to  the  weight 
the  pillar  is  to  bear. 

A  pair  of  such  logs,  7  ft.  apart  parallel  to  each  other,  are  laid 
directly  under  the  "bad  ground/'  and  on  top  of  these  are  laid 
two  more  at  right  angles  to  the  first  two,  the  same  distance  apart 
and  parallel  to  each  other.  Again  on  top  of  these  are  laid  two 
more  in  the  same  way.  The  pillar  is  thus  gradually  built  up  to 
the  back  and  eventually  wedged  down  tightly  by  lagging  and 


MINE  TIMBERING  115 

small  pieces  of  wood.  Considerable  experience  is  required  to 
make  a  tight  fit,  owing  to  the  unevenness  of  the  ground  and 
the  tendency  for  the  whole  to  shift.  All  the  pillars  are  inspected 
every  day  by  the  timber  boss  to  guard  against  any  such  failure. 
In  laying  one  cross  piece  on  top  of  another  there  is  great  tendency 
to  roll;  in  consequence,  notches  or  "  joggles,"  as  they  are  called, 
are  cut  in  the  lower  log,  into  which  the  upper  one  fits.  It  is  not 
usual  to  cut  them  more  than  3  in.  deep. 

Wooden  pillars  are  used  nearly  altogether  in  the  robbing  of 
the  ore  pillars  in  between  the  stopes.  These  ore  pillars  are  about 
25  ft.  through  from  stope  to  stope.  A  space  is  cut  out  of  the 
pillar,  about  9  ft.  through  and  the  width  of  the  lens,  if  the 
same  be  narrow,  and  8  ft.  high.  As  many  pillars  as  can  be  are 
built  in  this  space,  3  ft.  always  being  left  between  them  for 
walking  roads,  Sometimes,  instead  of  making  two  pillars  of  the 
foregoing  dimensions,  one  long  pillar  is  made  16x8  ft.  The 
inside  of  the  timber  pillar  is  now  filled  with  loose  rock,  This 
rock  steadies  the  pillar  and  takes  the  bulk  of  the  weight  when 
the  back  settles.  The  long  pieces  are  called  "edgers"  and  the 
shorter  ones  "cross  pieces."  When  these  pillars  are  securely 
wedged  against  the  back,  the  machines  are  set  to  work  again 
and  a  space  similar  to  the  first  is  mined  out  and  treated  with 
pillars.  This  process  is  carried  on  the  width  of  the  vein  and 
breadth  of  the  ore  pillar  until  all  the  ore  in  the  latter  rests  on 
timber.  The  stopes  on  either  side  are  now  filled  with  loose  rock 
to  the  level  of  the  top  of  the  timber  pillars,  likewise  the  spaces 
in  between  the  pillars,  and  the  process  of  mining  out  and  tim- 
bering proceeds  as  before,  the  timber  pillars  having  as  their  floor 
the  tops  of  pillars  of  the  slice  below.  The  level  of  the  rock  in 
the  stopes  is  kept  up  to  the  bottom  of  the  timber  pillars. 

DOCKS 

The  purpose  of  a  "dock"  is  to  hold  back  rock.  It  is  used 
where  loose  rock  is  pouring  down  upon  the  track  and  so  stopping 
the  trams;  likewise  in  filling  the  stopes,  as  before  mentioned. 

The  dock  is  a  simple  cribwork  like  the  timber  pillar.  Rock 
is  dumped  inside  and  then  the  running  rock  is  allowed  to  bank  up 
against  it.  The  double  length  16  ft.  is  more  usual  than  the 
single  in  docks.  To  save  timber  and  labor  the  inside  edgers  are 


116 


MINE  TIMBERING 


sometimes  done  away  with,  the  ends  of  the  cross  pieces  resting 
on  the  outer  edger  and  on  the  sloping  pile  of  rock.  As  the  work 
progresses,  a  couple  of  men  shovel  down  rock  and  thus  keep  the 
level  of  the  rock  up  to  the  required  hight  for  the  cross  pieces  to 
rest  upon.  (See  Fig.  95.) 


FIG.  95.  —  DOCKS. 

In  filling  the  stope  a  tunnel  must  be  left  for  the  trams,  hence 
on  both  sides  of  the  track  docks  are  built  to  a  hight  of  8  ft.  and 
are  filled  with  rock  in  and  behind.  A  double  layer  of  covering 
poles,  4  in.  in  diameter,  is  laid  across  from  one  dock  to  the  other 
and  the  whole  is  filled  over  with  rock.  It  is  considered  advisable 
to  leave  ample  space  overhead  in  the  tunnel,  because  the  pillars 
sink  sometimes  3  ft.  or  more,  owing  to  the  settling  of  the 
rock  filling.  It  is  found  that  the  hanging  wall  side  settles  much 
faster  than  the  foot-wall  side. 

The  spaces  between  the  logs  are  stopped  up  with  "filling 
pieces,"  to  prevent  the  rock  from  coming  out  into  the  tunnel. 

Mills  are  used  in  robbing  the  pillars,  to  convey  to  the  level 
below  the  ore  which  is  mined.  A  mill  might  be  called  the  con- 
verse of  a  timber  pillar.  It  is  cribwork  built  up  like  the  other, 
but  is  not  filled  with  rock.  Instead,  the  mill  is  covered  with 
cedar  lagging  on  the  outside  and  filled  around  with  rock. 

The  mill  is  built  in  the  same  relative  position  to  the  tunnel 
as  the  dock.  As  the  ore  is  taken  out  above,  it  is  dumped  into  the 


MINE  TIMBERING 


117 


oggle 


mill,  coming   out   into   a   tram  in  the  tunnel   by   means  of  a 
chute. 

The  mills  are  made  either  single  or  double,  being  5  ft.  4  in.  by 
5  ft.  4  in.,  or  5  ft.  4  in.  by  10  ft.  The  latter  is  the  more  usual  form, 
one  compartment  being  used  for  a  ladder  road,  the  other  to 
dump  rock  down. 

Filling  pieces  are  used  in  the  partition 
of  the  double  mill  to  prevent  rock  from 
coming  into  the  ladder-road.  (See  Fig. 
96.)  There  is  an  enormous  wear  and  tear 
on  the  mills,  due  to  the  falling  ore,  hence 
the  soundest  timber  is  used.  Hemlock  is 
preferred,  owing  to  its  toughness. 

The  life  of  a  mill  is  very  uncertain. 
On  an  average,  a  mill  lasts  three  months 
when  it  is  worked  night  and  day  for  six 
days  each  week.  What  then  happens  is 
that  the  pieces  of  ore  cut  through  the 
cribbing  pieces,  attacking  all  sides  of 
the  mill  impartially.  To  repair 
4  ft.  x6  =  in.  iron  plates  for  20  ft.  down  and  then  with  3-in.  planks. 
The  wear  and  tear  depends  upon  the  hight  of  the  mill,  the  kind 
of  timber  and  the  nature  of  the  ore.  The  diameter  of  the  pieces 
of  timber  is  from  10  to  18  in. 

It  is  customary  to  give  an  inclination  of  15  deg.  to  the  vertical 
in  the  mill,  in  order  to  break  the  fall  of  the  ore  and  so  save  the 
bottom  boards  of  the  chute,  and,  incidentally,  insure  safety  for 
trammers. 

CHUTES 

The  chutes  that  empty  the  mills  are  2  ft.  wide  at  the  smaller 
end,  widening  out  to  4  ft.  and  covering  all  the  floor  space  of  the 
mill.  They  have  an  inclination  of  45  deg.,  the  mouth  is  4  ft.  6  in. 
from  the  track  and  protrudes  1  ft.  into  the  tunnel.  All  chutes 
are  made  of  3x8-in.  planks.  Spaces  are  cut  out  of  the  cribbing 
pieces  of  the  mill  to  permit  the  chutes  to  be  made.  Chunks  of 
ore,  8  in.  or  less  in  diameter,  can  get  through  the  chute;  anything 
larger  than  this  sticks  and  has  to  be  "block-holed."  This  is  to 
be  avoided,  because  the  blasting  soon  destroys  both  mill  and 
chute.  (See  Fig.  97.)  In  the  case  of  the  square  chute,  the  ore 


FIG.  96.  — MILLS. 
mill,  it  is    lined  with  J-in. 


118  MINE  TIMBERING 

is  never  allowed  to  fall  directly  into  the  chute  from  any  hight 
over  8  ft.,  as  will  be  seen,  the  inclined  lagging  in  each  set  acting 
as  a  sort  of  chute. 

The  ore  is  kept  back  by  means  of  boards  fitting  into  slits  in 
the  sides  of  the  chute.  Sometimes  it  is  hard  to  send  these  planks 
into  place  and  so  complications  arise. 


FIG.  97.  —  A  TYPICAL  MILL  CHUTE. 

Notice  the  extra  cross  piece  for  the  double  mill;  also  the  pike  and  tram  bar 

beside  the  track. 

STAGING 

When  it  is  necessary  to  take  ore 'off  the  back  of  a  high  stope, 
the  drilling  machine  has  to  be  raised  within  a  few  feet  of  the 
place  to  be  mined.  This  is  done  by  means  of  staging.  A  stage 
consists  of  three  ladders,  each  at  the  apex  of  an  equilateral  triangle 
of  5-ft.  side.  The  ladders  are  inclined  outward  and  are  wedged 
against  the  back.  Planks  are  then  placed  on  the  rungs  of  the 
ladders,  so  as  to  make  a  platform.  The  machine  is  then  set  up 
on  this  platform.  At  the  best  it  is  a  very  shaky  affair  and  cannot 
be  carried  to  any  great  hight,  15  ft.  being  considered  a  very  good 
hight  for  the  platform  of  such  a  stage. 


MINE  TIMBERING  119 

LADDERS  AND  SOLLAES 

In  this  mine  the  ladders  all  have  an  inclination.  This  incli- 
nation tends  to  make  climbing  much  easier  and  safer.  The  poles 
of  the  ladders  are  made  of  3x5-in.  white  oak  scantling.  The 
rungs  or  "staves"  are  either  of  white  oak  or  iron,  the  former 
being  1J  in.  in  diameter,  the  latter  f  in.  in  diameter.  Under  the 
calked  boots  of  the  miners  they  are  soon  worn  through  and  are 
in  many  cases  left  too  long  for  safety. 

The  shaft  ladders  are  in  sections  of  20  ft.  The  sollars  are  15  ft. 
apart,  with  a  hole  in  each  large  enough  for  a  man  to  get  through 
with  ease.  The  end  of  the  ladder  protrudes  through  the  hole. 

The  ladders  in  other  parts  of  the  mine,  in  the  other  raises, 
for  instance,  are  much  longer,  and  are  made  by  bolting  together 
two  or  more  20-ft.  lengths  with  scantling,  on  the  outside.  The 
ladders  are  always  spragged  securely  to  prevent  shaking. 

The  sollars  are  a  great  means  of  safety  and  prevent  many 
serious  accidents,  especially  in  the  shaft,  where  it  is  now  impos- 
sible to  fall  more  than  20  ft.,  in  the  ladder  road,  that  is  to  say. 

MISCELLANEOUS 

The  timber-gang  in  full  force  is  eleven  strong,  counting  the 
boss.  Below  is  a  classification  of  the  men  in  the  mine. 

Captain    . $4.50  per  diem.  (?) 

Shift-bosses )  $2.50perdiem. 

Timber-bosses J 

Barn  boss    $2.30  per  diem. 

Timbermen $1.85  to  $2.00  per  diem. 

Miners   $2.10  per  diem. 

Helpers  to  miners    $1.85  per  diem. 

Contract  shaftmen (Paid  per  foot  of  shaft  sunk.) 

Ore  trimmers    . 


$1.85  per  diem. 
Rock  trimmers J 

Pumpmen j 

Track-layers !  Amount  of  wages  not 

Skip  tender j  ascertained. 

Track  cleaner J 

The  tools  of  the  timber-gang  are  few.     The  following  is  a  list 
of  their  whole  outfit : 

Wax  candles 5  per  day  of  10  hours. 

Two  saws hand  and  cross-cut. 

Axes one  per  man  (used  also  as  hammers). 


120  MINE  TIMBERING 

Spikes    various  sizes  (1-12  in.  long). 

Ropes various  sizes. 

Chain 8  ft.  long. 

Timber  truck. 
Log  pike. 

The  foregoing  information  was  obtained  at  Section  16  mine 
last  summer.  The  figures  given  are,  to  the  best  of  my  knowledge, 
accurate.  However,  the  character  of  the  mine  is  such  that  rules 
of  thumb  are  few  and  far  between.  When  a  problem  presents 
itself,  it  is  solved  according  to  the  ideas  of  the  particular  shift- 
boss  in  charge,  subject  to  the  approval  of  the  captain,  who  makes 
his  rounds  every  morning. 


OTHER    CONTRIBUTIONS 

THE  FRAMING    OF    RECTANGULAR    SHAFT    SETS 
BY  WILBUR  E.   SANDERS 

SQUARE-SET    PRACTICE    AT    BINGHAM,    UTAH 
BY   LOUIS  S.   GATES 

SQUARE-SET    TIMBERING    AT    BINGHAM,    UTAH 
BY   CLAUDE  T.   RICE 

MINE    TIMBERING    AT    LAKE    SUPERIOR 
BY  W.  R.  CRANE 

TIMBER    AND    TIMBERING    IN   THE   COEUR    D'ALENE 
BY   J.   H.   BATCHELLER 

TIMBERING  AT  THE  CHILLAGOE  MINES,  QUEENSLAND 
BY  T.   J.   GREENWAY 

TIMBERING    IN    TASMANIA 
BY  MARK  IRELAND 


THE   FRAMING   OF   RECTANGULAR   SHAFT   SETS1 
BY  WILBUR  E.  SANDERS 

THE  support  most  frequently  employed  for  preserving  the 
integrity  of  vertical  and  inclined  shafts  consists  of  a  rectangular 
frame  of  timber,  the  parts  of  which,  proportioned  to  any  required 
dimensions,  are  so  fitted  together  at  the  joints  as  to  form  a  con- 
nection that  will  weaken  the  timbers  forming  the  "  set "  or  frame 
in  the  least  possible  degree.  Many  methods  of  framing  the  joints 
have  been  employed  and  many  forms  of  joints  used,  but  those 
described  below  are  now  almost  universally  accepted  as  affording 
the  greatest  possible  strength  while  being  at  the  same  time  of 
comparatively  simple  construction.  Their  present  general  use 
may  be  said  to  represent  a  survival  of  the  fittest.  (See  Fig.  98.) 

The  connecting  joints  between  the  different  timbers  that  are 
assembled  to  form  the  shaft  set  are  made  up  of  various  shapes 
of  the  tenon  and  mortise,  the  gain  and  the  miter,  used  either 
singly  or  in  combination,  which  are  the  basis  of  all  joint  framing, 
however  much  they  may  vary  from  their  simple  forms  when 
employed  as  shoulders,  squared  or  beveled;  aiid  all  other  con- 
trivances whatsoever  for  bringing  together  from  two  or  more 
directions  the  parts  of  the  set  and  properly  connecting  them  at 
such  points.  In  general  it  may  be  assumed  that  the  pressure 
thrust  is  directed  from  without  inward  toward  the  center  of  the 
shaft,  and  it  is  for  the  purpose  of  opposing  or  resisting  this  pres- 
sure that  the  shaft  set  is  designed.  This  hypothesis,  however, 
is  true  only  in  part ;  for  through  causes  that  are  sometimes  known, 
but  often  are  unknown,  the  action  of  this  inward  pressure  becomes 
deflected  from  a  normal  direction  to  one  that  bears  upon  the 
frame  at  a  divergent  angle,  and  this  is  especially  true  with  regard 
to  inclined  shafts  in  certain  formations.  In  such  cases  the 
remedy  is  usually  applied  whenever  it  may  be  necessary,  subse- 
quent to  the  timbering  of  the  shaft. 

1  From  Engineering  and  Mining  Journal,  March  10,  1904,  Vol.  77. 

123 


124 


MINE  TIMBERING 


MINE  TIMBERING  125 

The  several  parts  of  shaft  sets  are  named  with  regard  to  their 
position  relative  to  the  shaft.  Primarily  the  frame  consists  of 
the  timbers  of  the  rectangular  set  proper,  together  with  those 
distance  pieces,  called  "posts/'  which  retain  it  in  position  at  a 
required  distance  from  the  adjacent  sets  above  and  below.  The 
rectangular  set  of  the  frame  is  made  up  of  jointed  timbers  that 
are  known  as  "plates."  While  all  of  the  plates  of  a  set  are 
properly  wall  plates,  yet  there  is  a  distinction  usually  made  in 
that  the  longer  pair,  those  paralleling  the  greater  axis  of  the 
shaft,  are  named  "  wall  plates  "  in  contradistinction  to  the  shorter 
pair  which  are  in  line  with,  or  parallel  to,  the  shorter  axis  of  the 
shaft,  and  which  are  known  as  "end  plates,"  or  briefly  "ends." 
This  designation  is  now  generally  applied  to  the  plates  of  both 
the  vertical  and  inclined  shafts,  although  it  is  probable  that  the 
name  originated  in  connection  with  the  timbering  of  the  latter, 
in  which  the  longer  timbers  of  the  set,  the  one  supporting  the 
hanging  wall  and  that  supporting  the  foot-wall  of  the  working, 
naturally  were  called  wall  plates,  and  this  significance  of  the  term 
was  finally  extended  to  comprehend  the  similar  longer  plates  of 
vertical  shafts  as  well. 

The  above  are  parts  belonging  to  the  simple  rectangular  set 
of  the  single  or  one-compartment  shaft,  but  the  cross-sectional 
area  of  larger  shafts  is  usually  divided,  for  purposes  of  traffic, 
ventilation,  and  the  accommodation  of  mining  appliances,  into 
two  or  more  compartments  separated  from  one  another  by  divi- 
sional girts  or  "centers."  In  sinking  through  firm  ground  the 
bottom  of  the  shaft  is  frequently  excavated  for  a  considerable 
distance  ahead  of,  or  below,  the  timber  supports,  in  order  that 
ample  space  may  be  afforded  for  the  placing  of  the  shaft  sets, 
and  to  remove  the  timbers  thereof  from  any  possibility  of  being 
shattered  or  displaced  by  heavy  blasts  beneath.  This  allows  the 
use  of  undivided  full-length  wall  plates.  In  some  ground,  how- 
ever,  this  is  not  permissible,  and  the  material  surrounding  the 
shaft,  through  which  it  is  being  driven,  may  be  of  such  texture 
as  will  make  it  imperative  that  the  timbering  shall  closely  follow, 
if  indeed  it  does  not  crowd,  the  excavation  of  the  working.  Under 
such  conditions  the  use  of  full-length  wall  plates  is  impossible, 
and  therefore  it  is  necessary  to  divide  or  "splice"  such  timbers 
that  they  may  be  brought  into  position.  The  girts  act  as  distance 
pieces  between  the  plates  in  order  to  preserve  the  width  of  the 


126  MINE  TIMBERING 

shaft.  At  the  points  of  division  of  the  wall  plates,  at  the  splices, 
the  girts  are  known  as  "splice  centers/'  while  those  used  to 
separate  the  compartments,  at  such  other  points  of  the  wall 
plates  as  are  not  spliced  but  solid,  receive  the  simple  designation 
of  "centers." 

Such  being  briefly  a  description  of  the  different  parts  that 
are  assembled  together  to  form  the  rectangular  shaft  set,  I  will 
proceed  to  discuss  the  methods  whereby  the  timbers  are  cut  and 
framed  in  order  that  they  may  properly  and  truly  join  together 
and  fit  exactly  at  the  joints.  (See  Fig.  99.)  I  will  assume  that 
they  are  of  the  desired  length,  and  that  they  are  square-sawed  to 
the  required  cross-sectional  area;  but  in  the  latter  instance  they 
are  certain  to  vary  slightly  from  the  exact  dimensions  and  often 
may  be  more  or  less  twisted.  One  side  or  face,  therefore,  is  se- 
lected —  the  most  perfect  and  even  one  —  if  there  should  be 
marked  imperfections,  and  this  face  is  taken  as  a  basis  of  opera- 
tions. 

It  is  necessary  in  the  first  place  that  this  face  shall  be  true, 
that  is,  without  bend  or  twist  as  regards  both  its  length  and  its 
breadth.  Care  in  this  particular  is  essential,  as  it  determines  the 
exactness  with  which  the  timber  shall  fit  its  companion  pieces  at 
their  common  joints  in  the  assembled  set;  and  therefore,  upon  a 
perfect  plane  throughout,  or  by  means  of  it,  depends  in  large 
measure  the  perfection  of  the  set  itself.  Where  extreme  precision 
is  required,  the  selected  face  is  worked  to  straight-edges,  sighting 
from  one  to  another  until  at  proper  points  the  face  has  been 
worked  to  line  with  the  assumed  plane  which  is  shown  when  the 
edges  of  the  straight-edges  are  brought  to  coincide;  bends  and 
twists  are  removed  locally  wherever  it  may  be  necessary  to  frame 
a  joint.  In  the  process  of  framing  many  prefer  to  select  for  this 
face  the  one  that  will  be  the  top  or  uppermost  side  of  the  timber 
when  in  its  place  in  the  set,  and  to  take  all  lines,  measurements 
and  angles  with  regard  to  it;  but  for  sufficient  reasons  I  believe 
that  the  basis  of  all  framing  should  preferably  be  that  which  will 
become  the  interior  face  of  the  piece  when  the  parts  shall  have 
been  assembled. 

Upon  this  face  a  center  or  base  line  is  marked  from  end  to 
end,  either  by  means  of  a  straight-edge  or  the  chalked  line,  and 
all  measurements  lengthwise  along  the  timber  are  laid  off  with 
reference  to  this  line,  as  also  are  those  crosswise  lines  which 


MINE  TIMBERING 


127 


locate  and  outline  the  shapes  of  the  joints  to  be  framed  upon 
the  selected  face,  the  relative  positions  thereof  having  been 
established  by  the  measurements.  This  base  line  represents  a 
line  at  which,  should  a  second  imaginary  plane  be  passed  length- 
wise through  the  center  of  the  timber  at  right  angles  to  the 


End 
Plate 

Hoisting  Compartment   Center   Hoisting  Compartment  center          Pun 

End 
ip  Compartment  Plate 

Positioi 

Position                                                   Position 

1                 WALL-PLATE      1 
E 

Positioi 
ight  and  Left 

I- 

^^ 

iBase  Line 

f%*,                    ^r^                    \i^                         \ 

SJ 

^r                 .i^r.                      it\ 

rag 

Mi 

'j-^JL                        /«y  /  i 

V       "Bevel                                     s  Center  Joint 
Halved-tenon                                                    E 

Splice-center  Joint                  Bevel     J 
Halved-tenon 

Gain  for  Post  END  PLATE          Two  thu3 


3"  Halved-tenon 


V"  Tenon     CENTER          One  ttma 


V"  Tenon 


G 


SPLICE  CENTER    Onethua 


P 


H 


FIG.  99.  —  LAYING  OUT  AND  FRAMING  RECTANGULAR  SHAFT  SET. 

plane  of  the  selected  face,  it  would  cut  or  coincide  with  the  latter 
throughout  its  length;  and  this  line  of  coincidence  of  the  two 
planes  we  have  fixed  upon  the  face  of  the  timber  by  marking, 
so  that  we  may  employ  it  as  a  basis  for  the  laying  out  and  framing 
of  the  joints.  (Fig.  99,  A  and  B.) 


128  MINE  TIMBERING 

Backward  from  this  face  to  required  distances  there  are  laid 
off  tenons,  mortises,  gains  and  miters  that  go  to  make  up  the 
joints  which  will  allow  the  different  parts  of  the  set  to  be  brought 
together  into  one  complete  and  perfectly  connected  whole. 
(Fig.  99  C.)  By  thus  taking  all  measurements  from  the  base  line 
toward  the  top  or  bottom  part  of  the  timber,  and  by  projecting 
the  points  and  lines  thus  established  backward  from  its  selected 
inner  face  towards  its  outer  face  or  back,  all  troubles  due  to 
twists  or  variations  in  the  size  or  shape  of  the  pieces  going  to 
make  up  a  properly  framed  set  may  be  overcome;  and  the  joints 
thus  framed  will  be  in  their  correct  relative  positions,  exact  in 
size  and  shape,  and  they  will  join  accurately  with  those  of  the 
other  connecting  parts  of  the  set.  It  is  needless  to  say  that 
exactness  in  the  fitting  together  of  the  joints  cannot  be  expected 
unless  all  necessary  precision  has  been  employed  in  their  framing. 

The  joints  that  must  be  framed  in  the  construction  of  a  set 
are:  those  at  the  corners  of  a  shaft,  which  connect  the  wall  plates 
and  the  end  plates  at  their  ends;  those  connecting  the  centers 
and  splice  centers  with  the  wall  plates  at  the  division  of  the 
compartments;  and,  where  it  is  required  or  used,  the  "boxing" 
of  the  ends  of  the  posts  into  the  frame  in  order  to  insure  that 
they  shall  retain  their  proper  positions.  The  framing  of  the 
wall  plates  and  the  methods  of  cutting  their  joints  are  shown  in 
Fig.  99  D  and  E;  that  of  the  end  plates,  Fig.  99  F;  of  the 
centers,  Fig.  99  G;  and  that  for  the  splice  center  in  Fig.  99  H. 

The  wall  plates  and  end  plates  are  joined  together  at  right 
angles  to  each  other  by  a  combination  of  the  tenon  and  miter, 
or  "bevel,"  as  the  latter  is  usually  designated.  The  thickness  of 
the  tenon  is  just  half  that  of  the  plate,  the  measurements  therefor 
being  taken  from  the  center  or  base  line  on  which  is  formed  one 
face  of  the  tenons,  their  lengths  being  equal  to  the  widths  of  the 
mating  tenons  of  the  joints.  The  wall  plates  invariably  have 
their  tenons  at  the  bottom  half  of  the  pieces  that  they  may 
support  the  end  plates  while  the  set  is  being  placed  in  position 
in  the  shaft,  the  tenons  of  the  end  plates  on  the  contrary  being 
framed  at  the  upper  half  of  the  ends  in  order  that  they  may  rest 
upon  and  be  supported  by  those  of  the  wall  plates  when  the  parts 
are  assembled.  This  halving  the  timbers  in  framing  tenon  for  the 
purpose  of  support  removes  just  one-half  of  their  cross-section 
and  thereby  weakens  the  pieces  at  such  points  proportionally. 


MINE  TIMBERING  129 

This  difficulty  is  overcome  by  the  use  of  a  half  right-angled 
miter,  of  45  deg.,  which  is  framed  from  the  face  of  the  timber 
backward  usually  to  a  depth  of  one  inch;  or,  in  other  words, 
the  piece  is  so  beveled  that  this  mitered  face  will  coincide 
with  and  abut  against  a  similar  miter  that  is  framed  upon  the 
companion  piece,  both  being  placed  in  the  same  relative  position 
within  the  joint.  By  means  of  this  construction  of  the  corner 
joints  of  a  shaft  set  it  is  brought  about  that  the  full  cross-section 
of  one  plate  engages  the  full  cross-section  of  its  companion  plate 
at  their  common  end,  at  which  point  the  two  pieces  are  at  right 
angles  to  each  other,  and  thereby  it  is  assured  that  the  full  strength 
of  one  of  the  timbers  supports  and  is  supported  by  the  full  strength 
of  the  other. 

In  the  case  of  the  simple  divisional  girts  or  centers,  instead 
of  tenoning  through  the  width  of  the  wall  plates  at  the  joints, 
as  do  the  ends  and  splice  centers,  they  are  connected  therewith 
by  a  short  V-shaped  tenon  that  is  mortised  into  a  corresponding 
gain  framed  into  the  inner  face  of  the  wall  plates  at  desired 
points,  the  tenon  being  narrower  at  the  bottom  than  at  the  top 
in  order  that  it  may  not  fall  or  be  forced  out  of  its  position. 
(Fig.  99  G.)  The  shoulders  of  this  tenon  should  be  constructed 
of  a  width  sufficient  to  engage  the  face  of  the  plate,  whereby  it 
may  afford  support  to  the  full  size  of  that  timber.  The  simple 
center  with  some  form  of  the  V-tenon  is  employed  for  the  pur- 
pose of  dividing  the  cross-sectional  area  of  a  shaft  into  com- 
partments, save  only  at  points  where  the  wall  plates  are  spliced 
in  order  to  shorten  them  so  that  they  may  be  brought  to  position 
in  confined  quarters. 

Whenever  it  becomes  necessary  to  shorten  the  wall  plates, 
the  timbers  are  so  cut  that  the  splice  will  coincide  with  the  length- 
wise center  line  of  one  of  the  cross  girts  or  centers  that  divide  the 
shaft  into  one  or  more  compartments.  Generally,  in  the  three- 
compartment  shaft,  which  has  been  taken  as  a  type  for  the 
reason  that  the  framing  of  all  of  the  different  joints  employed  in 
shaft  sets  may  be  shown  in  simple  detail,  this  cutting  in  two  or 
splicing  of  the  wall  plates  is  made  to  center  between  the  pump 
compartment  and  one  of  the  hoisting  compartments.  The  upper 
halves  of  the  wall  plates  at  such  points  are  removed  to  a  width 
that  is  somewhat  less  than  the  thickness  of  the  splice-center 
there  to  be  placed,  in  order  that  the  shoulders  extending  beyond 


130  MINE  TIMBERING 

the  sides  of  the  engaging  tenon  of  the  center  may  furnish  support 
against  side  pressure  to  the  full  cross-sectional  area,  and  therefore 
to  the  full  strength  of  the  plates  themselves.  (Fig.  99  E  and  H.) 

The  posts  are  not  framed,  although  they  should  be  cut  with 
precision  and  their  ends  properly  shaped  so  that  they  may  come 
truly  to  position  and  that  the  effects  resulting  from  any  twist  of 
the  timber  may  be  removed.  Almost  invariably  throughout  the 
metal  mines  of  the  western  United  States  gains  are  framed  into 
plates  and  centers  of  the  set  into  which  the  ends  of  the  posts  are 
boxed,  the  shoulders  of  these  gains  being  employed  to  support 
the  posts  in  place  against  the  inward  thrust  of  outside  pressure. 
(See  Figs.  98  and  99.)  On  the  other  hand,  the  general  practice 
throughout  the  eastern  portion  of  the  country,  in  metal  and 
coal  mining,  is  to  do  away  with  this  boxing  of  the  posts,  to  frame 
no  gains  for  their  reception,  but  to  set  them  flush  with  the  top 
and  bottom  faces  of  the  set,  and  to  depend  upon  the  tightness 
with  which  the  assembled  parts  are  blocked  and  wedged  into 
position  for  retaining  them  in  their  places. 

In  practice  certain  variations  of  these  several  joints  are  em- 
ployed, oftentimes  to  advantage,  but  the  above  discussion  is 
intended  to  describe  the  practical  methods  of  framing  the  typical 
rectangular  shaft  set. 


SQUARE-SET   PRACTICE  AT   BINGHAM,   UTAH1 

BY  Louis  S.  GATES 

BINGHAM,  situated  in  Salt  Lake  county,  Utah,  about  twenty- 
five  miles  south  of  Salt  Lake  City,  has  become  one  of  the  largest 
low-grade  copper  camps  in  the  West.  The  ore  occurs  in  large 
shoots  varying  from  50  to  200  ft.  in  width,  from  100  to  300  ft.  in 
length,  and  in  some  cases  proving  to  be  continuous  in  depth 
for  over  600  ft.  These  chambers  or  shoots  in  most  cases  have 
a  well-defined  foot-wall  of  quart zite  and  a  hanging  of  lime- 
stone, although  some  have  been  found  imbedded  entirely  in  the 
lime.  There  is  no  well-defined  dip  to  these  bodies  as  with  the 
veins,  and  they  are  found  varying  in  dip  from  the  horizontal  to 
the  vertical. 

The  ore  is  heavy,  running  about  9  cu.  ft.  to  the  ton,  and  carries 
on  an  average  25  to  30  per  cent,  iron,  20  to  25  per  cent,  silica, 
2  to  5  per  cent,  copper,  $1  to  S3  gold,  and  1  to  4  oz.  silver.  In 
mining  this  ore  great  care  is  exercised,  for  it  is  not  uniform  in 
texture,  changing  in  a  very  few  feet  from  hard  compact  sulphide 
to  a  soft  disintegrated  silicious  ore,  which,  unless  caught  up,  will 
run  and  cause  a  cave.  The  large  size  of  the  orebodies,  the  vari- 
able texture  of  the  heavy  ore,  and  the  added  disadvantage  of 
having  a  heavy  hanging  wall,  have  made  it  necessary  for  the 
square-set  system  to  be  universally  used  in  mining  the  large 
shoots. 

The  larger  companies  use  finished  Oregon  pine  timber  which 
is  framed  before 'shipment,  while  the  smaller  ones  frame  their 
timber  at  the  mine. 

The  sills  are  framed  from  6xlO-in.  timber  cut  5  ft.  long,  dapped 
1  in.  on  each  end  and  cut  in  4.5  in.  in  order  to  support  one- 
half  of  the  posts  on  each  end,  as  shown  in  Figs.  100  and  101. 
Occasionally,  where  long  caps  are  used  in  order  to  leave  out  a 

1  From  Engineering  and  Mining  Journal,  August  25,  1904,  Vol.  78. 

131 


132 


MINE  TIMBERING 


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MINE  TIMBERING 


133 


post  in  the  sets,  so  that  a  curve  may  be  made  in  the  track,  a 
long  10-ft.  sill  is  used.  Posts  are  cut  from  9xlO-in.  timber,  6  ft. 
8  in.  over  all,  and  are  framed  on  one  end  only,  the  base  setting 
into  the  sills  1  in.,  and  the  top  having  a  tenon  1  in.  long  and 
6x7.5  in.  The  caps  are  framed  on  both  ends,  as  shown  in  the 
sketches,  from  lOxlO-in.  timber,  and  since  they  are  framed  down 
into  the  posts  1  in.  it  is  evident  that  the  sets  are  5-ft.  centers  on 
the  sill  and  7  ft.  4-in.  centers  in  elevation.  The  braces  are  made 


FIG.  102.  —  TRANSVERSE  SECTION  OF  STOPE. 

from  6xlO-in.  timber  cut  4  ft.  4.5  in.  and  framed  as  shown  in  the 
sketch.  For  lagging,  2x8-in.  lumber  is  used;  any  heavier  than 
that  is  too  strong,  for  it  does  not  bend  enough  in  event  of  great 
weight  being  exerted,  nor  give  sufficient  warning  of  impending 
danger. 

The  size  and  extent  of  the  shoot  having  been  determined, 
there  are  two  methods  of  opening  up  the  stopes  dependent  upon 
the  character  and  dip  of  the  orebody  and  the  heaviness,  of  the 
hanging  wall.  The  preferable  method,  illustrated  by  Fig.  102, 


134  MINE  TIMBERING 

is  used  where  the  hanging  wall  is  firm  and  the  ore  solid,  allowing 
large  chambers  to  be  opened  up"  without  danger  of  excessive 
pressure  being  exerted  which  would  cave  the  stope.  A  definite 
level  having  been  determined,  the  sills  are  laid  for  the  first  set 
at  right  angles  to  the  general  strike  of  the  shoot.  The  sills  are 
only  5  ft.  long,  for  in  most  cases  it  is  inexpedient  to  open  enough 
ground  ahead  of  the  timber  to  lay  longer  sills.  The  sills  in  place 
and  tamped  down,  a  floor  of  single  lagging  is  laid  and  the  four 
posts  erected.  The  caps  are  placed  on  the  posts  in  the  same 
relative  position  as  the  sills  below,  and  braces  are  framed  to  fit 
the  top  of  post  and  cap,  thereby  completing  the  square  set;  no 
braces  or  girders  are  used  to  keep  the  posts  on  the  sills,  but  in 
their  stead  the  floor  lagging  is  laid  from  sill  to  sill,  and  a  notch 
is  cut  in  the  lagging  next  to  the  post  which  acts  as  a  foot  brace 
and  prevents  any  lateral  motion  of  the  post  on  the  sill.  A  double 
floor  of  lagging  is  placed  on  the  caps  and  braces  and  the  set  blocked 
securely,  completing  the  first  set  of  the  stope. 

This  first  set  having  been  placed  in  one  of  the  drifts,  as  near 
the  center  of  the  orebody  as  practicable,  a  row  of  lead  sets  is  now 
started  running  longitudinally  through  the  orebody;  after  this 
has  been  done,  or  the  sets  have  been  carried  ahead  four  or  five 
sets,  another  row  of  wing  sets  is  started  on  one  side  of  the  lead 
sets,  running  parallel  and  adjoining  them.  The  sill  floor  is  opened 
up  in  this  manner  until  four  or  five  rows  of  sets  have  been  carried 
along  before  st oping  on  the  floors  is  begun.  This  method  has 
been  found  more  economical,  for  after  once  getting  the  lead  sets 
through,  there  is  an  excellent  opportunity  to  slice  the  ore  off 
by  simply  starting  another  row  of  wing  sets,  and  it  affords  more 
place  for  the  machines  to  work  than  the  second  method. 

The  sill  floor  once  opened  up  sufficiently,  the  first  floor  is 
opened  up  exactly  as  the  sill,  by  driving  a  row  of  lead  sets  over 
the  lead  sets  on  the  sill  floor.  Care  is  always  taken  to  have  the 
sill  floor  at  least  two  and  preferably  four  rows  of  sets  wider 
than  the  first  floor,  thereby  making  it  easy  to  keep  the  broken 
ore  on  the  floors.  The  second  and  upper  floors  are  then  carried 
up,  the  object  being  to  carry  the  lead  sets  right  up  to  the  middle 
of  the  body,  thereby  relieving  the  weight  on  the  sill  floor  by 
resolving  the  downward  pressure  of  the  orebody  into  two  com- 
ponents, a  horizontal  one  resisted  by  caps  and  braces,  and  a  verti- 
cal component  resisted  by  posts.  The  stope  then  should  resemble 


MINE  TIMBERING 


135 


a  pyramid  of  blocks,  with  each  lower  layer  extending  one  or  two 
blocks  beyond  the  next  higher.  After  the  lead  sets  have  been 
carried  up  in  this  manner  the  floors  are  opened  out  by  continual 
slicing  until  the  walls  are  reached. 

The  second  method,  illustrated  by  Fig.  103,  is  used  where 
the  hanging  wall  is  very  heavy  and  there  would  be  great  danger 


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FIG.  103.  —  TRANSVERSE  SECTION  OF  STOPE. 

of  a  cave  were  the  first  method  used,  and  especially  where  the 
nature  and  extent  of  the  orebody  is  not  known.  In  this  case, 
as  in  the  first,  sills  and  caps  are  placed  at  right  angles  to  the 
general  strike  of  the  shoot,  but  instead  of  starting  at  the  center 
of  the  body  the  first  set  is  placed  as  near  the  hanging  wall  as 
possible  and  the  lead  sets  driven  along  the  hanging.  This  row 
being  driven  ahead,  a  second  row  is  started  adjoining  and  parallel 


136 


MINE  TIMBERING 


to  the  first.  After  two  rows  have  been  driven,  st oping  is  begun 
immediately  by  starting  a  row  of  sets  directly  over  the  second 
sill  row  and  carried  up  by  successive  floors  until  the  hanging 
wall  is  reached;  when  this  is  done,  another  row  is  driven  on  the 
sill  floor  and  the  sets  carried  up  to  the  hanging  wall.  The  stope 
is  continued  in  this  manner  until  worked  out  or  it  is  advisable 
to  cave  it  and  start  a  new  one. 


FIG.  104.  —  SHORT  SETS. 

The  double  advantage  of  this  method  is  manifest.  First, 
there  is  always  a  solid  breast  of  ore  on  one  side  of  the  stope,  which 
greatly  relieves  the  pressure  on  the  timbers;  second,  should  the 
stope  cave  in  unexpectedly,  only  the  ore  on  the  floors  and  in  the 
chutes  is  lost,  for  a  new  stope  can  be  opened  up  by  driving  a  row 
of  sets  on  the  sill  floor,  right  next  to  the  caved  stope,  and  then 
carrying  them  up  to  the  hanging  as  before.  On  approaching 


MINE  TIMBERING  137 

the  hanging  wall  it  is  evident  that  it  is  not  always  possible  to 
remove  all  the  ore  and  catch  the  hanging  wall  up  with  full  sets. 
In  such  cases  short  sets  are  used. 

Formerly,  when  a  short  set  was  used,  the  post  nearest  the 
hanging  was  cut  the  desired  length,  and  the  post  in  the  full  set, 
into  which  the  small  set  was  framed,  was  cut  the  same  length. 
The  cap  and  braces  were  placed  as  in  a  regular  set,  then  in  order 
to  complete  the  full  set  two  small  posts  were  framed  into  the  small 
set.  This  scheme  took  a  lot  of  time  and  weakened  the  posts 
of  the  full  set. 

In  order  to  overcome  this  disadvantage,  a  method  illustrated 
by  Fig.  104  is  used.  A  glance  at  this  sketch  shows  that  the  post 
of  the  short  set  is  placed  in  the  usual  position  on  the  cap  below, 
but  instead  of  cutting  the  post  in  the  full  set  in  two,  the  tenon 
on  the  cap  is  cut  off,  allowing  the  cap  to  butt  right  up  to  the  post. 
The  cap  is  spiked  to  the  post  to  hold  it  in  position,  and  a  piece 
of  2x8-in.  lagging  resting  on  the  cap  below  is  also  spiked  to  the 
post  and  forms  the  support.  To  prevent  lateral  motion  of  the 
caps  on  the  lagging,  two  pieces  of  2x8-in.  lagging  are  nailed  to- 
gether and  spiked  in  position  to  be  used  as  a  brace  on  the  end 
where  the  tenon  is  cut  off,  thereby  holding  the  cap  as  securely 
as  necessary.  This  method  is  simple  and  equally  as  efficient 
as  the  former,  as  it  answers  all  the  requirements. 

When  mining  on  the  foot-wall,  ground  posts  and  butt  caps  or 
butt  braces  are  used,  depending  on  the  steepness  of  the  foot- 
wall.  These  methods  are  shown  in  Fig.  105.  When  the  foot- 
wall  is  very  steep,  a  piece  of  lOxlO-in.  timber  is  framed  on  one 
end  as  a  cap  or  brace,  as  the  case  may  be,  to  fit  into  the  full  set, 
the  top  is  cut  1  in.  deep  and  9x10  in.  to  fit  the  posts,  and  the 
sides  1.25  in.  deep  by  6x10  in.,  or  1.25x9x10  in.  to  fit  the  brace  or 
cap,  and  cut  long  enough  to  fit  the  hitch  which  is  cut  into  the  foot- 
wall,  deep  enough  to  make  the  butt  cap  or  brace  secure. 

In  cases  where  the  foot-wall  slopes  off  so  much  that  it  is  im- 
possible to  place  the  butt  cap,  so  that  it  is  resting  on  solid  ground 
at  the  point  where  the  post  is  placed  on  it,  the  butt  cap  is  framed 
as  before,  except  that  the  bottom  is  cut  1  in.  deep  by  9x10  in.  to 
hold  a  post  which  affords  the  necessary  support  under  the  post 
which  is  placed  above  on  the  cap.  Frequently  spreaders  of  lag- 
ging are  placed,  extending  from  the  base  of  the  ground  post  to 
the  post  of  the  full  set,  to  hold  it  in  position. 


138 


MINE  TIMBERING 


When  a  post  shows  signs  of  weakness,  instead  of  putting  in  a 
false  set  to  strengthen  it,  angle  braces  are  used.  For  example, 
a  post  on  the  sill  floor  shows  signs  of  weakness;  the  angle  braces 
are  framed  to  fit  between  the  top  of  the  post  directly  over  the 
weakened  one  and  its  cap,  -and  extend  diagonally  downward 
to  fit  between  the  cap  and  the  foot  of  the  posts  on  each  side.  In 


FIG.  105.  —  BUTT  CAP  AND  GROUND  POST. 

this  manner  the  load  is  distributed  between  two  posts,  and  thus 
has  the  advantage  over  false  sets,  especially  on  the  sill  floor,  of 
not  decreasing  the  head  room. 

Economy  is  evident  in  all  workings.  For  often,  in  shooting, 
a  cap  or  brace  is  shot  down  on  the  post,  injuring  the  tenon;  in- 
stead of  a  new  piece  of  timber  being  put  in,  the  old  one  is  knocked 
back  in  position,  and  a  piece  of  lagging  spiked  to  the  side  of  each 
post  upon  which  the  injured  member  rests,  reaching  to  the  sill, 
or,  if  on  the  floors,  a  cap,  thus  forming  a  support  on  each  end 


MINE  TIMBERING  139 

and  relieving  the  pressure  on  the  broken  tenon  and  keeping  the 
injured  timber  in  place. 

In  blocking  the  sets  down,  care  is  used  to  see  that  the  timber- 
men  always  put  the  blocking  as  nearly  as  possible  over  the  posts 
and  never  near  the  center  of  the  brace  or  cap,  on  account  of  the 
leverage  exerted  on  the  timber,  should  the  set  take  weight.  When 
shooting,  especially  in  hard  ground,  the  timbers  are  faced  with 
old  lagging,  and  double  floors  are  used  to  prevent  large  boulders 
breaking  through  the  floors. 

When  much  waste  is  broken  in  stoping,  it  is  not  run  over  the 
dump,  but,  instead,  certain  sets  are  lagged  up  to  the  hanging  wall 
and  the  waste  thrown  in  to  be  used  as  filling,  making  columns 
which  greatly  aid  in  holding  back  the  ground.  When  a  stope 
has  been  worked  out,  floors,  pipes,  ladders  and  everything  mov- 
able are  taken  out  and  1-in.  holes  bored  in  nearly  all  of  the  posts 
in  the  sill  floor;  powder  is  inserted  and  the  whole  round  is  shot 
by  a  battery,  caving  the  stope. 


SQUARE-SET  TIMBERING   AT   BINGHAM,   UTAH1 
BY  CLAUDE  T.  RICE 

AT  present  square-set  timbering  is  mainly  used  in  mining  the 
orebodies  at  Bingham  Canon,  Utah.  As  the  orebodies  are  mainly 
replacement  deposits  in  the  limestone  along  mineralizing  fissures, 
the  walls  of  the  orebodies  are  generally  strong  except  where  the 
limestone  has  been  shattered  by  faulting.  Because  of  this  strength 
of  wall,  complete  filling  of  the  stopes  with  waste,  such  as  is  the 
practice  at  Butte,  Mont.,  where  in  some  of  the  square-set  stopes 
the  filling  or  "gob"  is  kept  within  two  floors  of  the  roof  of  the 
stope,  is  not  required. 

MINING  METHODS 

Consequently  the  orebodies  of  Bingham  are  mined  without 
much  waste  filling,  thus  resembling  the  open  square-set  stopes 
of  some  of  the  Leadville  mines  where  the  ores  also  occur  in  lime- 
stone. Whenever  a  stope  shows  signs  of  a  "taking  weight"  a 
few  square  sets  are  lagged  and  waste  is  dumped  into  this  pen, 
forming  a  waste-filled  bulkhead  which  helps  materially  to  steady 
the  stope.  These  "pen"  bulkheads  work  so  satisfactorily  that  I 
failed  to  see  any  wooden  bulkheads  such  as  are  used  in  some  of 
the  Boston  &  Montana  mines  at  Butte. 

The  chutes  are  simply  plank-lagged  square  sets  with  occa- 
sional offsets  to  break  the  fall.  Owing  to  the  softness  of  these 
sulphide  ores  there  is  no  excessive  amount  of  cutting  of  the 
lining  of  the  chutes,  and  consequently  neither  "bricked"  chutes 
nor  the  open  staggered  chutes  which  characterized  the  open 
square-set  stopes  of  the  Homestake  mine,  at  Lead,  S.  D.,  are 
necessary.  Two-inch  planks  are  used  for  floors  in  the  stopes. 
Owing  to  the  strength  of  the  ore  and  the  little  tendency  it  has 
to  scale  off,  the  roof  sets  of  the  stope  generally  do  not  have  to 

1  From  Engineering  and  Mining  Journal,  Nov.  3,  1906,  Vol.  82. 

140 


MINE  TIMBERING 


141 


be  lagged,  another  feature  which  makes  the  timbering  and  mining 
cost  in  Bingham  Canon  square-set  stopes  much  less  than  at 
Butte,  Montana. 

THE  SQUARE-SET  SYSTEM 

However,  the  mine  managers  at  Bingham  have  not  been 
quite  satisfied  with  these  advantages,  but  have  designed,  in  order 
to  save  timber,  a  specially  framed  square  set,  which,  at  least  as 


-6-9- 


Bottom 


POST 


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Cap  \ 

/    Cap                Cap        V 

III 

IU 

Perspective  View 
Plan  Side  View 

FIG.  106.  —  DETAILS  OF  SQUARE-SET  TIMBERING. 

far  as  my  experience  indicates,  is  peculiar  to  these  mines.  This 
system  was  first  used  at  the  Highland  Boy  mine  of  the  Utah 
Consolidated  and  has  later  been  adopted  at  the  near-by  Boston 
Consolidated  mine.  It  has  proved  so  satisfactory  that  the  same 
framing  of  square  sets  is  used  at  the  Cactus  mine  at  Newhouse, 
Utah,  which  like  the  Boston  Consolidated  is  under  the  control  of 
Samuel  Newhouse. 

On  the  Comstock  lode  the  original  square  sets  were  framed 
as  designed  by  Philip  Deidesheimer,  with  the  horns  of  the  posts 


142  MINE  TIMBERING 

butting  against  those  of  the  posts  below.  This  framing  is  still 
retained  in  the  few  square  sets  used  at  present  on  the  Comstock. 
Whether  the  downward  pressure  there  is  greater  than  the  side 
pressure,  as  the  framing  would  indicate,  I  do  not  know,  but  I 
could  not  help  noticing  this  feature  of  the  framing  of  the  original 
square  sets,  which  to  me  at  least  is  unique;  for  although  I  have 
worked  in  many  mines,  and  visited  many  more,  in  which  square- 
set  timbering  is  used,  I  have  not  seen  elsewhere  this  feature  of 
butting  the  posts  against  each  other. 

PECULIARITIES  OF  THE  BINGHAM  PRACTICE 

At  Bingham  Canon  the  sets  are  designed  to  offer  the  greatest 
resistance  to  side  pressure  and  so  the  horns  of  the  caps  are  caused 
to  butt  against  each  other,  the  cap  being  10x10  in.  square. 
In  this  butting  of  the  caps  there  is  nothing  unusual,  but  in  the 
posts  we  have  the  unique  feature  of  a  piece  rectangular  in  section 
instead  of  square,  the  post  being  10  in.  wide  in  the  direction  of 
the  girts  and  9  in.  wide  cap-ways,  thus  saving  an  inch  in  the 
cross-section  of  the  posts.  Moreover,  the  posts  have  a  bottom 
and  a  top  end,  for  they  are  "bald"  at  the  bottom  and  have  only 
a  1-in.  horn  on  top.  In  consequence  of  this  framing  of  the  post, 
the  top  mortise  made  up  by  the  assembling  of  the  caps  and  girts 
differs  from  the  bottom  mortise,  and  so  there  is  a  top  side  and 
bottom  side  to  the  caps  and  girts.  This  at  first  confuses  the 
green  timber  man  used  to  caps  without  a  bottom  or  top  side, 
but  of  course  this  is  no  valid  objection  to  this  square  set.  Nat- 
urally, it  is  necessary  to  have  a  tenon  on  the  top  end  of  the  post 
on  which  to  rest  the  caps  and  girts.  As  the  botlbom  of  the  post 
rests  on  the  caps  and  girts  it  does  not  need  to  be  framed,  but  it 
seems  to  me  that  it  would  be  just  as  well  to  have  the  top  and 
the  bottom  ends  of  the  posts  similarly  framed  with  horns,  for 
then  there  would  be  no  such  complicated  arrangement  of  framing 
as  the  present  design  demands  in  the  caps  and  girts.  True,  that 
would  cause  an  extra  pass  of  the  post  in  the  framer,  but  it  would 
avoid  the  special  framing  of  a  cap  only  on  the  top  side  of  the 
girt.  If  the  similar  framing  of  both  ends  of  the  post  were  adopted 
the  girt  would  be  a  plain  6xlO-in.  timber  resembling  the  girt 
used  by  F.  A.  Heinze  at  the  Cora-Rock  Island  mine  at  Butte, 
Mont.,  where  (if  my  memory  be  correct)  the  girts  are  plain, 


MINE  TIMBERING  143 

8x10  in.,  and  the  posts  are  10x10  in.  with  horns  on  both  ends,  and 
the  caps  are  10x10  in.  butting  up  against  one  another. 

CRITICISM  OF  THE  SYSTEM 

This  making  of  the  girt  only  6x10  in.  in  cross-section  ap- 
pears to  be  a  step  in  the  right  direction;  for  the  purpose  of 
the  girt  or  tie,  or,  as  it  is  better  called  in  some  camps,  the  brace, 
is  mainly  to  resist  the  side  movement  of  the  caps  and  is  not  to 
resist  any  great  inward  pressure  in  the  stope  as  is  the  function 
of  the  cap.  Consequently  the  girt  does  not  have  to  be  as  strong 
as  the  cap.  In  my  opinion  it  is  a  waste  of  timber  to  make  the 
girts  equal  in  cross-section  to  the  caps. 

Another  feature  that  strikes  me  as  worthy  of  consideration  is 
the  fact  that  although  the  vertical  distance  in  the  clear  between 
the  caps  and  the  posts  is  6  ft.  5  in.,  the  distance  in  the  clear  cap- 
ways  and  girt-ways  in  the  sets  is  only  a  little  over  4  ft.  It  might 
be  possible  to  increase  this  distance,  and  effect  still  more  economy 
in  the  timbering  without  endangering  the  stope,  but  this  last 
matter  of  course  is  a  point  for  men  well  acquainted  with  the 
ground  to  decide,  and  undoubtedly  it  has  been  given  much  thought 
by  the  Highland  Boy  management,  which  is  noted  for  its  high 
efficiency.  I  mentioned  the  point  only  because  of  the  striking 
difference  in  these  dimensions,  which  the  managements  of  these 
mines  have  thought  necessary.  The  only  drawback  to  the  girt 
being  as  narrow  as  6  in.  is  the  ease  with  which  a  floor  can  be 
torn  up  by  a  heavy  blast  in  the  stope,  unless  the  floor  is  tightly 
wedged  in  place,  for  it  has  only  a  3-in.  hold  when  laid  cap- 
ways.  But  this,  of  course,  is  a  very  small  drawback. 

All  these  timbers  are  framed  at  the  mills  in  Oregon  and 
Washington,  and  are  shipped  ready  to  go  into  the  stopes. 

The  arrangement  of  the  sets  is  shown  in  Fig.  106. 

Owing  to  the  fact  that  the  dimensions  were  scaled  to  the 
timbers  themselves  and  not  taken  from  a  drawing,  there  may  be 
some  slight  mistakes  (even  J  in.)  in  some  of  the  dimensions,  but 
the  dimensions  of  the  sets  are  in  the  main  correct. 


MINE  TIMBERING  AT   LAKE   SUPERIOR1 
BY  W.  R.  CRANE 

MUCH  timbering  is  done  in  the  copper  mines  of  northern 
Michigan,  although  in  many  of  them  the  use  of  timber  is  confined 
almost  exclusively  to  the  shafts,  pillars  being  depended  upon  for 
support  of  the  hanging  wall  in  the  stopes.  The  problem  of 
support  of  workings  several  thousand  feet  distant,  vertically, 
below  the  surface  is  becoming  more  difficult  of  solution  with  the 
lapse  of  time,  owing  to  the  rapidly  increasing  area  of  workings 
only  partially  supported,  and  to  a  less  extent  to  the  collapse  of 
the  supports,  pillars,  or  timber  in  the  upper  levels.  The  enormous 
loads  thrown  upon  the  hanging  walls  of  large  open  stopes,  which 
are  supported  by  pillars  or  timbers  of  only  a  very  small  propor- 
tionate part  of  the  total  area  exposed,  must  ultimately  cause 
their  disintegration,  which,  when  it  occurs,  may  start  a  move- 
ment that  may  be  very  slight,  yet  the  results  would  be  difficult 
to  conjecture. 

Where  portions  of  the  vein  filling  are  left  for  support  of  hanging 
wall,  the  idea  is  to  remove  ultimately  as  much  of  it  as  possible 
before  it  collapses  and  before  any  fall  of  roof  would  interfere 
with  the  operations  carried  on  below.  No  systematic  attempt 
has  been  made  to  rob  pillars,  except  in  the  filling  system,  in  which 
case  those  left  standing  and  finally  removed  are  the  floor  or  chain 
pillars.  That  none  too  large  pillars  are  left  for  the  support  of 
the  hanging  wall  is  evidenced  by  the  rapid  breaking  up  of  such 
unmined  portions,  and  that,  too,  in  the  course  of  but  a  few  years. 

Timbering  may  be  used  as  an  auxiliary  to  pillars,  and  alone, 
even,  as  temporary  support,  and  is  in  fact  employed  extensively 
both  ways.  Probably  mine  support  by  timbering  is  carried  on 
most  extensively  and  systematically  in  the  Calumet  and  Hecla 
and  the  Tamarack  mines,  which  are  among  the  largest  and  deepest 
in  the  district.  It  would  seem,  after  the  disturbances  which  have 

1  From  Engineering  and  Mining  Journal,  Nov.  10,  1906,  Vol.  82. 

144 


MINE  TIMBERING 


145 


recently  occurred  in  several  of  the  mines  of  this  district,  that 
ultimately  filling  of  the  stopes  with  waste  must  be  the  solution 
of  the  problem  of  support.  No  attempt  is  made  in  this  connection 
to  give  details  of  all  of  the  forms  of  timbering  employed,  but 
rather  to  make  note  of  only  a  few  typical  forms  which  have  come 
under  our  observation. 


TIMBERING  IN  SHAFTS 

The  method  of  sinking  practically  all  of  the  shafts  through 
the  surface  materials,  which  are  usually  sands  and  gravels,  is  by 
drop  shafts,  consisting  of  frames  and 
studdles  forming  sets,  to  which  ad- 
ditions can  be  made  indefinitely.  These 
sets,  when  securely  bound  together  by 
bolts  and  inclosed  in  a  sheathing  of 
lagging,  maintain  the  shape  and  aline- 
ment  of  the  shaft  and  keep  out  any 
quicksand  that  might  enter  otherwise. 
Below  the  point  where  the  surface 
materials  terminate,  and  where  the 
shafts  enter  solid  rock,  often  no 
timbering  is  necessary,  for  a  time  at 
least,  the  excavation  being  self-sup- 
porting. 

The  arrangement  of  the  timbering 
used  in  self-supporting   excavations  is 
shown  in  Fig.  107.    The  long  sleepers, 
running    transversely   with  the  shaft, 
are  set  in  hitches   cut  in  the  sides  of 
the    shaft,    and    are    carefully   alined 
with  the  finished   portion.    Timbering 
in  this  manner  is  done  in  reverse  order 
to  shaft  sinking,  i.e.,  is  carried  on  from 
below  upward,  the  object  being  to  fa- 
cilitate  matters.     Timbers   are   placed    FIG.  107.  —  SHAFT  TIMBER- 
up  to  the  rock   pentice,  which  is  left       ING'    Plan  and  section' 
as   a    protection    to    the   operations   in   the   shaft    below,  and 
when  it  is  removed,  only  a  few  pieces  of  timber  remain  to  be  put 
in  place  to  complete  the  support  of  the  tracks,  ladders,  etc.     The 


146 


MINE  TIMBERING 


alinement  of  sleepers  placed  in  this  manner  is  rendered  consid- 
erably more  difficult  than  if  carried  downward  continuously  from 
the  finished  shaft  above,  the  work  of  alinement  having  to  be 
carried  on  through  the  small  sinking  shaft  and  to  a  point  100  ft. 
below  the  end  of  the  working  portion. 


FIG.  108.  —  LEVEL  TIMBERING  AND  SQUARE  SETTING. 


1.  Sill 

2.  Foot  Knee 

3.  Hanging  Knee 

4.  Post 

5.  Stull 

6.  Filler 

7.  Starter 


8.  Hanging  Post 

9.  Center  Post 

10.  Studdle 

11.  Leg 

12.  Double  Ender 

13.  Lagging 

14.  Bottom  Wall  Plate 


15.  Wall  Plate 

16.  Blocking 

17.  Stull 

18.  Post  or  Strut 

19.  Flat  Cap 

20.  Props 


The  sleepers  having  been  placed  and  securely  wedged  in 
position,  the  ties  are  next  put  in  position,  being  set  alternately 
with  ends  overlapping.  The  sleepers  are  12x12  in.  by  17  ft. 
8  in.  and  are  spaced  8  ft.  apart,  center  to  center.  There  are  six 
7x8-in.  or  7xlO-in.  ties  placed  between  two  adjacent  sleepers. 
A  partition  4  ft.  high  separates  the  hoisting  compartments  from 
the  manway,  which  is  4  ft.  wide.  Posts  (10x10  in.),  set  be- 
tween the  foot-  and  hanging  walls,  support  the  2-in.  planking 
of  the  partition,  which  serves  as  a  protection  against  falling  rock 


MINE  TIMBERING  147 

to  men  passing  up  and  down  in  the  manway.     Wooden  ladders 
are  fastened  to  the  sleepers  as  shown  in  Fig.  107. 

On  the  up-shaft  side  of  the  sleepers  are  fastened  planks,  which 
extend  from  the  top  of  the  sleepers  to  the  bottom  of  the  shaft 
excavation,  thus  dividing  that  portion  of  the  shaft  flush  with  the 
tops  of  the  sleepers  and  ties  into  sections  or  pockets,  as  it  were, 
by  the  plank  dams.  These  sections  are  filled  with  fine  mine 
dirt,  the  placing  of  the  dirt  being  accomplished  by  a  small  skip 
of  about  two  tons  capacity,  which  is  provided  with  a  small  gate 
at  the  lower  part  of  the  rear  end.  A  load  of  dirt  is  hoisted  to 
the  point  in  the  shaft  desired  and  the  gate  is  opened  by  simply 
unlatching  it,  when  the  dirt  runs  out  and  is  spread  largely  by 
gravity. 

CONCRETE  LINING 

When  the  shaft  excavation  is  not  self-supporting,  the  framing 
employed  in  the  quicksand  and  other  surface  materials,  or  similar 
forms,  is  resorted  to,  usually,  however,  without  lagging.  Aside 
from  timbering,  concrete  linings  are  occasionally  employed,  which 
reach  from  the  surface  to  bed  rock,  with  which  connection  is 
made,  thus  effectively  shutting  off  the  water  that  is  often  en- 
countered in  large  quantities  in  the  loose  surface  accumulations 
of  gravel  and  sand.  Concrete  is  also  used  in  the  rock  excavation 
of  shafts,  where  it  serves  as  support  for  the  tracks,  being  built 
either  in  transverse  ties  or  longitudinal  stringers  for  the  rails  to 
rest  upon  and  be  fastened  to  by  long  bolts  passing  through  plates 
in  the  body  of  the  structure. 

TIMBERING  IN  DRIFTS  AND  STOPES 

In  the  workings,  i.e.,  levels  and  stopes,  timbering  takes  the 
form  of  stulls  and  square  sets,  and  all  imaginable  combinations 
of  the  two.  In  the  deeper  levels  of  the  Tamarack  mines,  stulls, 
both  in  the  form  of  individual  members  and  in  groups  of  three 
or  four,  set  close  together  (commonly  known  as  batteries  of 
stulls),  are  extensively  employed.  The  batteries  are  spaced  from 
8  to  10  ft.  apart  and  may  be  used  in  combination  with  individual 
stulls.  Stull  timbers  range  in  size  from  1  to  4  ft.  in  diameter. 
They  are  carefully  measured  and  cut  on  the  surface,  and  then 
carried  below  and  set  normal  to  the  lode,  being  wedged  fast. 


MINE  TIMBERING 


r 


M.. 

oS 


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Ch 

s« 

F 

i 

0 

1 

1  , 

*-- 

-1 

1 

MINE  TIMBERING  149 

The  arrangement  of  timbers  employed  in  levels,  which  serves 
as  a  basis  for  the  building  of  square  sets  in  stopes,  is  shown  in 
Fig.  108.  Further,  square  setting  may  be  stopped  at  any  time 
and  the  face  of  the  timbering  covered  with  lagging  as  shown. 
One  form  of  square-set  joining  is  shown  in  Fig.  109.  The  forms 
of  the  individual  members  are  shown  in  three  projections  each, 
from  A  to  G,  while  in  H  is  shown  a  combination  of  A,  B  and  C 
(a  joint  for  a  standard  set) ,  and  in  I  are  grouped  F  and  G  and  a 
form  of  C.  The  arrangement  of  timbers  shown  in  H  is  a  plan  of 
the  joint  at  A,  Fig.  108,  while  in  I  is  shown  a  plan  of  the  joint  B. 
The  blind  double  ender  D  is  used  with  B  and  C  in  joint  at  C. 
In  H  and  I  the  dotted  lines  represent  the  members  above  and 
below  the  plane  of  the  plan  given,  always  similar,  but  not  neces- 
sarily vertical. 

Timber  caps,  or  wall  pieces,  usually  rough  round  logs,  are 
also  employed,  being  supported  by  pack  walls  built  along  the 
lines  of  the  levels.  A  lagging  of  rough  poles  is  placed  on  the 
caps  and  waste  rock  piled  on  these  in  turn.  Levels  are  thus 
formed  and  maintained  in  the  Baltic  and  Trimountain  mines, 
where  filling  methods  are  employed;  often  as  much  as  30  to  50 
ft.  of  waste  filling  may  rest  upon  the  caps. 

Timber  as  a  means  of  support  for  the  mines  has  a  wide  range 
of  usefulness  in  this  district  and  will  always  be  an  important 
factor  in  mining  regardless  of  the  methods  employed. 


TIMBER  AND  TIMBERING  IN  THE  COEUR 
D'ALENE  * 

BY  J.  H.  BATCHELLER 

THE  timber  principally  used  is  fir  and  tamarack.  Bull  pine, 
in  large  sticks,  seems  to  mildew  and  rot  too  rapidly  for  good 
service,  though  in  the  form  of  planks,  spiling,  track  ties  and 
wedges  it  does  well  enough.  Fir  and  tamarack  seem  to  resist 
decay  equally  well,  even  in  old  workings.  There  is,  however,  one 
limitation  to  the  use  of  tamarack :  it  bears  end  pressure  well,  but 
is  too  brittle  to  give  good  service  under  any  side  or  transverse 
stress.  Because  of  this  failing,  tamarack  is  rarely  sawed  into 
square  timbers,  such  as  caps,  ties,  etc.,  but  it  is  cut  into  posts, 
stulls,  helpers,  angle  braces,  sprags,  poles,  chute  cribbing  and 
chute  lining,  Fir  not  only  serves  for  all  of  the  above,  but  is  also 
cut  into  sills,  caps,  ties,  and  plates. 

In  a  general  way,  there  are  four  different  principles  recognized 
as  making  for  economy  in  timbering:  first,  the  utilization  of 
all  the  products  from  cutting  the  raw  material;  second,  the  use 
of  simple,  framed  joints;  third,  the  adapting  of  the  size  and 
number  of  timbers  used  to  the  duty  required;  and,  fourth,  the 
use  of  a  uniform  system  of  timbering  throughout  the  mines. 

The  saving  under  the  first  head  is  accomplished  in  the  follow- 
ing way:  The  trimmings  made  in  squaring  timbers  are  cut  into 
5-ft.  lengths  called  "slabs,"  which  are  used  in  covering  square 
sets  under  bulkheads,  and  in  cribbing  waste-fillings.  The  vends 
of  large  round  timbers  —  too  short  for  squaring  into  caps,  ties, 
or  collar  braces  —  down  to  about  2.5  ft.  in  length,  are  framed 
with  a  top  tenon  4x4x7  in.  long  (Fig.  110)  on  one  end  and 
left  flat  on  the  other.  They  are  used  for  foot-wall  stope-set 
posts  (Figs.  115  and  116).  Ends  shorter  than  2.5  ft.  are  cut 
into  wedges. 

1  From  Engineering  and  Mining  Journal,  Sept.  15,  22,  29,  1904,  Vol.  78. 

150 


MINE  TIMBERING 


151 


The  planks  —  2,  3  and  4  in.  thick  —  are  purchased  ready 
cut.  The  2-in.  planks  are  used  in  chutes,  flooring,  and  as 
spreader  boards  in  tunnel  sets.  Three-inch  planks,  5  ft. 
long,  are  employed  for  flooring  and  short  chutes.  Three-  and 
4-in.  planks  8  and  10  ft.  long  are  used  in  temporary  slide  chutes 
in  newly  started  stopes,  before  they  are  cut  out  high  enough  for 
permanent  cribbed  chutes.  The  lagging  is  split  cedar,  5  ft. 
long,  and  used  in  bulkheads  (Figs.  113,  114  and  115),  waste  cribs, 


Plan  of  Bulkhead 
SCALE 
0  1  2  Feet 

FIGS.  110-114.  —  SQUARE-SET  TIMBERS. 

and  as  temporary  sprags  and  blocks,  around  newly  erected  square 
sets.  The  economy  of  material  is  almost  perfect.  A  given  stick 
of  round  timber  will  yield  but  little  to  go  into  the  refuse  pile,  as 
the  series  of  useful  articles  runs  from  quadruple  ties  19  ft.  8  in. 
by  8  ft.  10  in.,  down  to  short  chute  cribbing  3  ft.  10  in.  long 
by  4  in.  diameter. 

Under  the  second  principle  governing  economy,  a  system  of 
framing  has  been  worked  out  to  conform  with  the  idea,  first, 
that  the  less  the  end  of  a  timber  is  cut  to  make  a  joint,  the  stronger 
the  joint;  and,  second,  that  all  joints  are  a  source  of  weakness. 


152 


MINE  TIMBERING 


Simple  joints  not  only  economize  material,  but  cost  less  in  framing 
and  in  labor  of  erecting.  Under  the  first,  note  the  framed  ends  of 
the  square-set  timbers  (Figs.  110,  111,  112  and  115),  of  the  tunnel- 
set  timbers  (Figs.  118  and  119),  and  of  the  shaft  set  timbers 
(Figs.  120  and  121). 

In  the  framing  of  square  sets  there  are  several  advantages  in 
having  the  top  tenon  of  the  post  longer  than  the  bottom  one. 
This  arrangement  leaves  only  a  shallow  hole,  the  bottom  of  which 
is  easily  reached  with  the  fingers,  to  be  cleaned  out  of  the  joint 
to  make  ready  for  stoping  a  new  post.  At  the  top  end,  the  longer 
tenon  not  only  gives  a  better  hold  on  the  newly  placed  cap  and 
tie,  but  also  gives  a  better  chance  to  block  the  post  itself  to  the 


FIG.  115.  —  SQUARE-SET  TIMBERS. 

ground.  The  straight  tunnel-set  timbers  have  no  framing  what- 
ever save  only  the  shallow  notch  cut  on  the  inside  of  the  posts, 
at  the  top.  This  serves  merely  as  a  shoulder  on  which  the  spreader" 
board  can  rest.  In  the  battered  sets,  the  under  side  of  the  cap 
is  notched  at  the  ends,  to  leave  a  portion  in  the  center  for  a 
spreader  to  the  posts;  then  the  ends  are  beveled  merely  enough 
to  give  the  square  ends  of  the  posts  a  firm  seat.  In  both  styles 
of  sets,  the  full  cross-section  strength  of  the  posts  is  retained. 
The  loss  of  strength  to  the  cap  of  a  battered  set,  from  notching 
the  under  side  at  the  ends,  is  partially  made  up  by  its  having 
less  distance  to  span  than  the  straight-set  cap.  The  inclined- 
shaft  sets  are  of  far  greater  strength,  under  this  system  of  fram- 
ing, than  under  the  vertical-shaft  system,  where  the  plates  are 


MINE  TIMBERING 


153 


joined  with  half-splice  tenons.  This  method  is  possible  in  in- 
clined shafts,  where  the  end  plates  carry  but  little  side  pressure, 
and  it  gives  full  cross-section  strength  to  the  timbers  holding 
the  wall  plates. 


01234    5  Feet  |>  I 

FIGS.  116  AND  117.  —  SQUARE-SET  STOPE. 

In  recognizing  that  all  joints  are  a  source  of  weakness,  note 
the  use  of  double,  triple,  and  quadruple  ties  (Figs.  116  and  117). 
At  first  thought,  it  might  seem  that  this  point  does  not  concern 
the  matter  of  "simple  framed  joints."  However,  as  there  is  a 


154 


MINE  TIMBERING 


limit  to  the  length  and  size  of  timbers  that  can  be  used,  there 
will  have  to  be  many  joints.  By  using  long  ties,  the  joints  where 
they  are  supported  by  helpers  are  the  simplest  and  strongest  for 


BATTERED  TUNNEL  SET 


Hi 
H 

STRAIGHT  TUNNEL  SET 


10  x  18 


012  Feet 

FIG.  118.  —  BATTERED  AND  STRAIGHT  TUNNEL  SETS. 

the  work,  as  they  are  merely  butt-end  bearings.  Owing  to  the 
limited  size  of  the  drawing,  no  full-length  quadruple  tie  is  shown 
in  Figs.  116  and  117.  They  are,  however,  extensively  used  on 


MINE   TIMBERING 


155 


the  sill  and  second  floors  of  stopes.  Above  the  second  sets  in  a 
stope,  they  become  impracticable  because  their  length  makes 
them  too  difficult  to  handle.  Triple  ties  can  be  used  in  many 
places  for  three  or  four  sets  up,  but  at  last  they,  too,  are  dis- 
carded when  it  becomes  too  difficult  to  get  them  into  place. 
Double  ties  can  be  turned  anywhere,  and  are  used  wherever 
possible. 

The  third  principle  —  that  of  adapting  the  size  and  the 
number  of  timbers  to  be  used,  to  the  duty  required  —  is  illus- 
trated in  every  feature  of  the  methods  of  timbering,  and  consti- 
tutes one  of  the  most  important  points  of  economy.  The  term 
"duty"  must  be  understood  to  mean  not  only  the  amount  of 
immediate  weight  a  timber  must  hold,  but  also  the  probable 


FIG.  119.  —  TUNNEL-SET  TIMBERS. 

future  weight  and  length  of  time  it  will  be  desired  to  hold.  Note 
(Figs.  116  and  117)  how  the  light  stope  sets  are  used  like  stagings 
to  work  on,  while  the  weight  of  the  ground  is  carried  principally 
by  the  waste  filling.  Where  the  ground  gets  too  heavy  for  the 
stope  sets  alone,  the  small,  inexpensive,  unframed  helpers  and 
angle  braces  are  put  in  alongside  of  the  square-set  posts  to  give 
local  relief,  sufficient  to  serve  until  filling  is  completed  around 
these  places.  On  the  top  floors,  wherever  suspicious  pieces  of 
ground  threaten  to  fall  in  large  masses,  big  stulls,  sometimes 
footed  against  the  timbers,  and  sometimes  on  the  filling,  are  put 
in  temporarily  until  the  ground  is  taken  down  and  square  sets 
erected. 

Two  sizes  of  helpers  are  used:  Center  helpers,  8  to  10  in.  butt 
diameter;  and  side  helpers,  6  to  8  in.  diameter.     Center  helpers 


156 


MINE  TIMBERING 


are  placed  under  the  long  ties,  in  the  positions  where  framed 
posts  would  come,  if  the  sets  were  of  short  length.  Side  helpers 
are  put  next  to  framed  posts  to  hold  up  the  failing  ends  of  caps 
and  ties.  Angle  braces  are  put  in  to  prevent  the  sets  from 
"riding"  (or  leaning).  The  tops  and  bottoms  of  the  posts, 
against  which  they  are  set,  must  have  either  tenons  or  sprags  to 
hold  against  the  side  thrust.  This  merely  means  that  angle 
braces  do  no  good  if  placed  against  the  flat-bottomed  helpers 
unless  the  latter  are  strongly  held  from  being  pushed  out  of 
position.  Sometimes  two  angle  braces  are  put  in  to  lean  against 


in           n            n 

1                                      10*x  10* 

I 

*<c 

PLAN 

k 

X 

'•~2 

_ 

H 

Kg 

-^        10'x  10' 

^ 

*s 

t                       ' 

-- 

;  —  «  —  , 

1 

2 

J 

END 

00 

ELEVATION 

\ 

£3                              STJ 

FIG.  120.  —  TWO-COMPARTMENT  SHAFT. 

each  other,  like  a  triangular  truss,  to  take  the  place  of  a  post,  or 
center  helper  (Figs.  116  and  122).  In  this  case  the  object  is  to 
take  all  possible  weight  from  above  the  center  of  a  drift  and 
transfer  it  to  the  sides.  All  angle  braces,  stulls  and  helpers  are 
sawed  to  measure  at  the  time  of  erection,  and  are  cut  to  drive 
home  tight.  They  are  always  put  in  butt-end  up,  as  it  has  been 
found  they  do  not  split  lengthwise  as  readily  that  way  as  with 
the  small  end  up. 

The  use  of  long  ties  —  when  the  ground  does  not  break  too 
short  to  be  opened  up  sufficiently  —  offers  a  number  of  advan- 
tages. Not  only  does  it  save  one,  two,  or  three  framed  posts, 


MINE  TIMBERING 


157 


respectively  —  as  the  ties  are  double,  triple,  or  quadruple  length 
—  but  also  just  twice  the  number  of  caps  as  posts  (that  is,  two 
caps  for  each  post).  Further,  there  is  a  saving  in  size  of  the 
timbers  put  in  the  place  of  the  posts.  The  strength  of  a  9-in. 
center  helper  is  greater  than  the  transverse  strength  of  the 
8xlO-in.  tie  on  top,  for  the  latter  will  almost  invariably  break 
first,  or  mash  down,  or  turn  over,  before  the  helper  fails.  This  is 
a  saving  of  two  inches  in  the  diameter  of  the  timber,  for  framed 
posts,  on  an  average,  are  never  less  than  11  in.  in  diameter  when 


8  Outside  Posts  6*x  6* 
1  Inside  Post    12"x  6* 


I0"x  10*           \_J 

3 

10"x  10*                                                      K           ®~"~ 

i 

S 

t« 

n 

PLAN 

50 

i  17 

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WxW              F«^ 

10'xlO"           ^ 

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.i 

f 

M 

2 

•i 
T 

J 

\,    Skipway 

Manway 

r 

10"x  10" 

8*x  10" 

Chute 

Chute 

s 

o 

i 

END 
ELEVATION 

I0"x  10" 

t&        aw'x  10"       GT 

FIG.  121.  —  FOUR-COMPARTMENT  SHAFT. 

round,  and  they  are,  of  course,  cut  from  still  larger  timber  when 
squared  to  10x10  in.  In  place  of  the  two  caps  saved  where 
each  center  helper  goes,  small  sprags  or  girts  are  put  in  and 
driven  tight. 

Besides  the  matter  of  economy,  the  long  ties  have  the  advan- 
tage of  greater  strength.  Where  a  tie  extends  over  the  top  of  a 
helper,  all  the  top  fibers  of  the  timber  lend  their  tensile  strength 
to  the  others  in  the  span,  which  is  not  the  case  where  a  joint 
occurs.  The  use  of  long  ties  has  also  a  marked  tendency  to 


158 


MINE  TIMBERING 


stiffen  the  stope  timbers,  and  makes  it  easier  to  hold  them  all  in 
good  condition  till  filling  is  completed.  This  advantage  of  stiffen- 
ing the  stope  timbers  amounts  to  a  great  deal  where  cribbed 
chutes  come  up  every  four  sets,  from  one  end  of  the  stope  to  the 
other,  parallel  with  the  pitch  of  the  ore  shoot.  As  ties  are  always 
placed  across  the  stope  —  from  foot  to  hanging  —  the  chutes 
come  up  between  them.  The  slope  of  a  chute  often  necessitates 
the  removal  of  a  cap,  thus  greatly  weakening  the  joints  of  the 
two  sets  on  either  side.  However,  where  long  ties  are  used  on 
either  side,  at  the  point  where  a  chute  crosses  a  set,  there  are  no 
caps  in  the  way,  and  the  girts  are  moved  merely  enough  to  give 
clearance. 


FIG.  122.  —  ANGLE  BRACES. 

The  system  of  using  double  drift  sets  (Figs.  116,  117  and  124), 
at  points  where  long  life  and  power  to  bear  great  weight  are 
desired,  is  another  important  feature  in  the  timbering  practice. 
These  sets  are  usually  put  up  only  where  a  drift  or  a  station  is 
to  be  kept  open  for  a  long  while  under  a  filled  stope.  As  the 
outside  posts  and  cap  in  no  way  affect  the  inner  set,  the  single 
set  undergoes  no  break  or  change  where  it  joins  or  leaves  the 
double  portion. 

The  use  of  a  uniform  system  of  timbering  permits  of  a  saving 
not  only  in  material,  but  also  in  labor.  All  stope,  drift,  adit,  and 
shaft  sets,  and  stulls  holding  filling,  are  put  in  5  ft.  apart  —  center 
to  center.  Flooring  planks,  slabs,  lagging  and  poles  are  cut  a 
bare  inch  short  of  5  ft.  long;  so  that  they  can  be  used  equally 


MINE  TIMBERING 


159 


well  in  all  parts  of  the  mine.  Another,  though  minor  point,  is 
that  the  caps  and  ties  are  of  the  same  cross-section;  therefore,  if 
required,  a  cap  can  always  be  framed  from  a  tie.  The  uniformity 
of  system  lessens  the  amount  of  dimension  stuff  necessary  to  hold 
in  stock,  and  saves  many  minor  delays  to  the  timber  gangs 
underground. 

The  foregoing  remarks  cover  some  of  the  details  of  the  methods, 
but  are  concerned  mostly  with  their  economic  side.  There  is, 
however,  an  equal  or  larger  number  of  points  that  are  of  great 
importance  to  the  efficiency  of  all  timbering.  Attention  can  best 


FIG.  123.  —  STANDARD  STOPE  SET. 

be  called  to  some  of  these  in  connection  with  a  running  comment 
on  the  accompanying  figures. 

On  comparing  Figs.  110-114,  116,  117  and  123  with  Figs. 
115  and  122,  it  will  be  noticed  that  the  latter  show  round 
stope-set  posts,  while  in  the  former  they  are  shown  square. 
They  were  drawn  square  purely  as  a  matter  of  convenience,  and, 
furthermore,  though  not  especially  common,  posts  10x10  in. 
square  occasionally  come  in  from  the  sawmill.  The  average  size 
is  11  in.  butt  diameter.  This  does  not  occasion  any  loss  in  strength 
to  the  square  sets.  The  cross-section  area  of  the  lOxlO-in. 
stick  is  only  100  sq.  in.,  as  against  95  sq.  in.  cross-section  of  the 
11-in.  round  post.  Examination  of  the  details  of  the  bearing 


160 


MINE  TIMBERING 


surfaces  of  caps  and  ties  shows  that  on  a  lOxlO-in.  post  each 
cap  will  cover  16  sq.  in.,  and  each  tie  24  sq.  in.  The  total  area 
of  cross-section  can  be  accounted  for  as  follows: 

2  caps  at  16  sq.  in.  each 32  sq.  in. 

2  ties  at  24  sq.  in.  each 48  sq.  in. 

1  tenon,  4x4  in.  square 16  sq.  in. 

Total   surface   bearing  weight 96  sq.  in. 

Balance  remaining  unused 4  sq.  in. 

Total  cross-section  area 100  sq.  in. 


FIG.  124.  —  DOUBLE  DRIFT  SETS. 

For  all  practical  purposes  the  95-sq.  in.  cross-section  of  the 
11-in.  post  gives  as  good  service  as  the  96-sq.  in.  useful  bearing 
surface  of  the  lOxlO-in.  post.  There  is  yet  another  advan- 
tage, besides  the  economical  one  already  pointed  out.  Of  the 
two  sizes,  the  round  post,  though  smaller,  will  invariably  be  the 
stronger,  because  it  possesses  all  the  strength  of  the  original 
outside  fibers  of  the  timber,  while  the  squared  post  is  weakened 
by  having  them  cut. 

The  figures  given  above  show  that  the  ties  have  50  per  cent, 
more  bearing  surface  on  the  posts  than  the  caps.  This  fact 


MINE  TIMBERING  161 

indicates  clearly  the  reason  why  bulkheads  should  always  be 
started  from  the  ties  rather  than  across  the  caps.  In  the  details 
of  a  bulkhead  (Figs.  113,  114  and  115),  observe  that  the  planks 
from  which  it  starts  are  laid  across  the  ties.  In  erecting,  the 
lagging  is  cribbed  up  till  there  is  not  room  for  more,  then  blocks 
are  put  in  and  wedged  as  tight  as  it  is  possible  to  strike  them. 
Owing  to  their  inconvenient  position,  it  is  often  impossible  to 
jamb  the  whole  bulkhead  tight  by  means  of  the  top  wedges 
alone.  To  accomplish  this,  wedges  are  driven  in  at  the  four 
corners  below,  over  the  planks,  and  the  whole  structure  is  keyed 
up  tight.  This  is  of  prime  importance,  for  the  bulkhead  is 
needed,  not  only  to  hold  the  ground  from  slacking  away,  but  in 
steadying  the  square  sets  from  swinging  when  shots  are  fired 
near  by.  It  is  also  important  that  all  newly  erected  timbers 
should  be  tightly  blocked  and  spragged  from  the  ends  to  the 
ground;  likewise  all  flat-bottomed  posts  and  helpers,  wherever 
they  may  be  in  danger  of  being  shot  out.  It  is  only  by  holding 
all  timbers  rigid  that  stope  sets  can  be  held  from  "riding."  When 
once  "riding"  starts,  it  is  not  only  difficult  but  expensive  to 
stop. 

The  foundation  planks  of  a  bulkhead  are  usually  cut  with  a 
saw,  5  in.  back  from  each  end,  5  in.  deep,  on  the  sides  that  overlie 
the  caps;  so  that  when  a  new  post  is  to  be  erected  on  top  of  one 
of  those  by  the  bulkhead,  one  blow  from  an  ax  will  knock  off 
the  5x5-in.  block,  and  make  room,  without  chopping  the 
grit-covered  planks,  for  the  foot  of  the  post.  As  the  cedar  lag- 
ging is  softer  than  the  wood  in  the  planks  and  timbers,  the  con- 
dition of  a  bulkhead  always  gives  first  warning,  by  its  state  of 
compression,  of  the  square  sets  taking  any  excessive  weight. 
Though  not  shown  in  the  drawing,  slabs  are  frequently  used 
across  the  ties,  between  the  foundation  planks,  to  serve  as  a 
covering  to  the  sets.  These  slabs  never  carry  any  of  the  weight, 
but  merely  keep  small  rocks  from  sloughing  off  on  the  men  below. 
Bulkhead  material  can  be  used  over  and  over,  till  too  badly 
crushed  and  broken  to  bear  weight.  After  that  it  —  and  all 
other  useless  truck  —  is  thrown  into  the  waste  fillings.  Where 
long  ties  are  used,  bulkheads  are  built  in  exactly  the  same  man- 
ner, in  units;  only  two,  three  or  four  are  erected  to  correspond 
with  the  length  of  the  tie. 

Figures  116  and  117  show  some  features  of  interest.     After 


162  MINE  TIMBERING 

the  timbers  around  and  above  the  tunnel  sets  were  well  secured 
by  filling,  the  direction  of  the  sets  was  changed  from  having 
the  ties  point  perpendicularly  to  the  direction  of  the  adit  and 
the  strike  of  the  vein  till  the  ties  lay  parallel  with  the  axis  of  the 
ore  shoot.  The  pitch  of  the  orebodies  rarely  coincides  with  the 
dip  of  the  foot-wall.  Most  commonly  it  lies  at  some  oblique 
angle.  Where  the  erection  of  angle  sets  begins,  it  is  sometimes 
necessary  to  use  horizontal  braces  or  sprags,  from  the  straight 
(the  original)  sets,  diagonally  or  cornerwise  through  the  angle  sets 
over  to  the  foot-wall.  This  diagonal  bracing  ceases  naturally 
when  the  original  straight  sets  are  worked  out  against  the  hanging 
wall  of  the  stppe;  and  the  connection  between  the  two  classes  of 
sets  is  held  by  filling. 

The  particular  advantage  of  turning  the  sets  lies  in  the  pos- 
sibility of  keeping  the  chutes  always  along  in  the  stope,  and 
those  that  start  in  the  stope  at  the  sill  floor  can  be  carried  clear 
up  to  the  level  above.  If  the  sets  were  continued  as  begun, 
perpendicular  to  the  strike,  the  chutes  at  one  end  of  the  sill 
floor  would  soon  run  into  barren  ground  above  the  ore  shoot, 
while  at  the  other  end  the  stope  would  soon  reach  diagonally  up 
and  beyond  the  last  chute  started  in  ore  on  the  level.  From  this 
level,  on  this  side,  it  would  then  become  necessary  to  run  raises 
through  barren  ground  in  order  to  get  chutes  up  to  the  stope 
for  ore.  There  would  be  no  way  to  avoid  the  condition,  for  the 
ore  chutes  could  not  well  be  made  small  enough  to  turn  diagonally 
up  through  the  stope  sets  without  their  being  too  small  for  any 
service. 

Two  sizes  are  used,  known  as  foot-wall  and  hanging  wall 
chutes.  The  former  are  4  ft.  high  by  3  ft.  wide  in  the  clear 
inside,  and  the  latter  3x3  ft.  inside.  The  chute  cribbing  is 
round  and  varies  from  4  to  10  in.  in  diameter.  The  ends  are 
sawed  so  as  to  leave  a  flat  tenon  5  in.  long  by  3,  4,  or  5  in.  thick, 
according  to  the  diameter  of  the  stick.  (Fig.  119.)  With  a 
5-in.  tenon  on  each  end,  and  the  inside  clearance  of  3  and  4  ft. 
respectively,  the  cribbing  measure  is  3  ft.  10  in.  and  4  ft.  10  in. 
The  inside  clearance  between  stope  posts  and  ties  is  practically 
4  ft.  2  in.,  so  there  is  ample  room  in  which  to  build  chutes  and 
make  the  turn  necessary  where  the  angle  sets  start  away  from 
the  straight  sets.  Manways  are  made  in  exactly  the  same  way 
as  the  foot-wall  chutes,  4x3  ft.,  but  are  always  built  entirely 


MINE  TIMBERING  163 

separate  from  them  on  the  foot-wall.  The  hanging  wall  chutes 
are  made  as  branches  of  the  foot-wall,  so  that  all  the  ore  can  be 
handled  from  one  gangway. 

Sometimes  stopes  are  started  from  the  sill  floor  in  a  slightly 
different  manner  from  that  indicated  in  Figs.  116  and  117.  Sill- 
floor  posts  8.5  ft.  in  the  clear,  with  flat  bottom  and  a  4x4 
x7-in.  top  tenon,  are  used.  On  top  of  these  regular  stope-ties 
and  caps  are  placed.  Pillars  of  cribbed  filling  are  put  in  to  hold 
the  stope  above,  and  a  heavy  covering  floor  is  laid  over  the 
gangways  and  stations  left  open  between  the  pillars.  On  top  of 
the  pillars  and  heavy  flooring  are  laid  the  stope  sills  proper,  for 
the  regular  7-ft.  square-set  posts,  entirely  independent  of  the 
sill  floor  below.  When  this  procedure  is  followed,  the  single 
tunnel  set  is  usually  enough,  and  the  cap  is  braced  by  means  of 
an  extension  or  heavy  sprag  put  in  against  the  end  from  a  hitch 
cut  in  the  foot-wall. 

However  a  stope  may  be  timbered  above,  it  is  always  started 
on  good  sills.  These  are  covered  with  stout  poles  to  hold  the 
filling  against  the  time  when  the  ore  in  the  floor  will  be  taken 
out  by  stoping  from  a  level  below. 

In  closing  the  comments  directed  solely  to  stope  timbering, 
there  are  some  interesting  points  worthy  of  comparison  between 
the  7-ft.  clear  sets  used  in  the  Bunker  Hill  and  Sullivan  Com- 
pany's mines,  and  the  6-ft.  clear  sets  used  by  some  other  mining 
companies.  It  must  be  remembered  that  in  each  case  the  thick- 
ness of  the  flooring  planks  must  be  deducted  from  these  measure- 
ments, which  leaves  these  sets  with  6  ft.  9  in.  walking  room,  as 
against  5  ft.  9  in.  in  the  clear  for  the  others.  The  longer  posts 
give  greater  efficiency  to  the  working  powers  of  the  men  in  the 
stope.  For  example,  only  an  exceptionally  tall  man  would  be 
unable  to  walk  erect,  with  timbers  or  steel  on  his  shoulders,  in  a 
6  ft.  9-in.  clearance.  Furthermore,  angle  braces  frequently  have 
to  be  put  in  where  a  passageway  is  being  used  to  reach  a  chute. 
A  7-in.  angle  brace  put  in  across  a  7-ft.  square  set,  still  leaves 
room  for  a  man  to  run  the  average  sized  iron  wheelbarrow  under 
it;  while  the  same  timber  between  6-ft.  posts  would  stop  the  way. 

As  a  matter  of  economy,  the  longer  posts  are  desirable.  It 
would  take  only  41  posts  7  ft.  10  in.  long  to  gain  a  vertical  hight 
of  321  ft.  2  in.  against  47  posts  6  ft.  10  in.  for  the  same  distance. 
This  means  a  total  saving  of  6  long  posts,  or  of  one  7  ft.  10-in. 


164  MINE  TIMBERING 

post  in  every  53  ft.  8  in.  In  a  stope  of  given  hight,  there  is  not, 
of  course,  any  saving  in  the  number  of  feet  of  timber  put  in  ver- 
tically, but  the  use  of  the  longer  posts  saves  the  cost  of  one  com- 
plete floor  for  the  whole  stope  —  caps,  ties,  general  material, 
and  labor  —  in  every  53  ft.  8  in.  vertical. 

Figure  118  needs  but  little  comment.  The  battered  tunnel 
sets  are  the  cheaper,  both  in  material  and  in  the  amount  of 
ground  necessary  to  be  broken  out.  The  posts  are  frequently 
given  more  batter,  where  the  ground  is  softer  and  has  more  side 
weight.  The  drawing  represents  the  minimum  amount. 

Since  they  are  not  put  up  on  sills,  battered  sets  are  not  used 
in  places  where  the  floor  will  be  worked  out  from  below.  The 
straight  tunnel  sets  have  top  and  bottom  spreader  boards  spiked 
to  the  caps  and  sills.  There  are  several  sizes  used  in  the  mines, 
varying  slightly  in  the  hight  of  the  posts  as  well  as  in  the  dimen- 
sions of  the  timbers.  The  choice  of  a  given  size  is  governed  by 
the  place  where  the  sets  are  wanted,  and  the  duty  they  must 
fulfil.  Double  tunnel  sets  are  made  by  placing  an  extra  large 
straight  set  outside  of  the  ordinary  single  set.  Figures  116,  117, 
and  118  show  the  double  sets,  and  7-ft.  square  sets  erected  side 
by  side  from  the  same  floor.  The  principal  point  is  that  tunnel 
sets  of  any  style  should  always  be  made,  as  nearly  as  possible, 
free  and  independent  of  the  stone  sets;  so  that  any  settling  or 
swinging  of  the  latter  will  not  affect  the  gangway. 

The  inclined  shaft  sets  shown  in  Figs.  120  and  121  have  already 
received  comment.  Where  the  inclination  is  not  too  great,  the 
V  tenon  and  mortise  joint  can  be  omitted,  and  then  a  two-com- 
partment shaft  set  becomes  nothing  more  than  a  two-compart- 
ment tunnel  set,  on  a  slope  instead  of  horizontal.  This  latter 
method  of  timbering  is  successfully  used  in  one  45-degree  shaft. 
The  limits  governing  its  general  use  would  be  the  amount  of  side 
pressure  the  end  plates  would  have  to  carry,  and  also  the  increas- 
ing difficulty  of  erecting  as  the  slope  becomes  greater;  since  there 
would  be  no  V  tenons  and  mortises  to  hold  the  end  plates  from 
dropping  out  while  the  set  was  being  blocked  and  wedged. 

Figures  125  and  126  show  the  general  arrangement  of  the 
timbers  at  shaft  stations  on  levels.  The  dotted  lines  in  Fig.  126 
show  the  chutes  cut  in  the  rock,  just  outside  the  shaft  covering, 
connecting  the  places  where  the  cars  are  dumped  at  the  station 
with  the  chutes  in  the  bottom  compartments  of  the  shaft. 


MINE  TIMBERING 


165 


Figures  127  and  131  show  some  points  in  detail  that  are  quite 
common  in  use.  Figure  127  shows  how  segments  should  be 
framed  to  support  a  long  station  cap,  when  the  load  is  uniformly 
distributed  along  the  cap.  The  plane  of  the  joints  should  be  so 
cut  as  to  bisect  the  angle  formed  by  the  intersection  of  the  two 


FIG.  125.  —  TWO-COMPARTMENT  SHAFT  STATION. 

adjacent  segments.  This  practically  gives  them  the  same  shape 
and  carrying  strength  as  an  arch.  Figure  130  shows  at  a  glance 
how  the  framing  should  not  be  done.  The  center  segment  would 
not  carry  any  load,  but  would  act  merely  as  a  spreader.  Further- 
more, the  vertical  side  segments  would  carry  but  little  weight, 
while  the  sloping  side  segments  would  thrust  almost  entirely  out- 


166 


MINE  TIMBERING 


ward.  Figure  129  shows  the  manner  of  holding  up  slope  timbers 
so  that  a  post  can  be  cut  off.  There  is  no  opportunity  for  choice 
as  to  how  the  top  ends  of  the  sloping  segments  should  be  framed, 
but  at  the  bottom  ends  a  method  is  shown  which  is  better  than 
in  Fig.  130,  though  not  as  good  as  in  Fig.  127.  The  only  advan- 
tage of  this  method  in  Fig.  129  is  that  the  vertical  side  segments 
do  not  have  to  be  as  large  timbers  as  in  the  others.  For  the 
sake  of  simplicity  in  the  drawings,  it  is  not  indicated  that  the 
posts  of  sets  must  be  held  against  the  side  thrust  of  the  segments 
by  fillings  or  sprags. 


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FIG.  126.  —  FOUR-COMPARTMENT  SHAFT  SET. 

Figure  131  shows  the  details  of  the  framing  of  two  angle 
braces  put  in  from  one  floor  up  to  the  tie  or  cap  of  the  set  above, 
to  hold  a  load  concentrated  at  one  point.  It  is  similar  to  the 
method  shown  in  Figs.  116  and  122,  save  that  in  this  case  the 
timber  supported  runs  across  the  direction  of  the  angle  braces. 
In  these  cases  no  sprags  or  cribbed  fillings  are  necessary  to  hold 
the  side  posts,  for  the  thrust  is  resisted  by  the  bottom  tenons. 
Figure  128  shows  how  a  tunnel  may  be  widened,  say  to  make 
room  for  a  double  track,  without  discarding  all  the  timbers  in 
place.  This  method,  however,  cannot  be  used  unless  the  con- 


MINE   TIMBERING 


167 


dition  of  the  ground  is  favorable,  for  there  is  the  weakness  of 
two  joints  on  that  side,  instead  of  one.  In  good  ground,  the 
short  side  post  may  even  be  safely  dispensed  with,  and  a  hitch 
can  be  cut  in  the  foot-wall  for  the  bottom  end  of  the  sloping 
segment. 

Slight  mention  has  been  made  of  stull  timbering.  It  is  a 
large  and  important  part  of  the  work,  though  there  are  but  few 
details  that  seem  to  lend  themselves  to  description.  Neverthe- 
less, it  calls  for  as  much,  if  not  greater,  skill  and  judgment  on 


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'"6       1       2      3      4      5  Feet 

FIGS.  127-131.  —  DETAILS  OF  FRAMING. 

the  part  of  the  timberman  to  point  his  stulls  and  balance  the 
ground  to  the  best  advantage,  as  in  any  other  work.  A  few 
features  are  shown  in  Figs.  132  and  133.  It  is  always  preferable 
to  build  the  chutes  on  the  foot,  not  only  to  get  all  the  steepness 
of  grade  possible,  but  also  because  it  is  more  convenient  for  load- 
ing cars  when  the  level  is  run  on  a  bench  cut  in  the  foot-wall.  It 
is  desirable  to  run  a  level  thus,  in  order  that  it  may  be  left  intact 
when  the  next  stope  from  below  comes  through  the  ore  left  in 
the  bottom.  Sometimes,  when  the  stope  is  not  too  high  and 


168 


MINE  TIMBERING 


the  slope  is  sufficiently  steep,  no  cribbed  chute  is  built  at  all. 
In  this  case  the  broken  rock  runs  down  over  the  foot-wall  in  a 
passage  kept  open  between  two  rows  of  stulls,  lagged  and  filled 
on  the  outside.  Figure  133  shows  a  cribbed  manway  built  up 
into  the  stope  alongside  of  the  ore  chute. 


FIGS.   132  AND  133.  —  STULL  STOPE. 

Before  closing  these  notes  on  timbering  in  the  Bunker  Hill 
and  Sullivan  mines,  some  figures  of  costs  in  regard  to  square-set 
timbering  will  be  of  interest.  Exclusive  of  the  initial  cost  of 
material  and  freight,  the  total  cost  of  square -set  posts,  caps,  and 
ties,  delivered  at  the  mouth  of  the  mine,  is  as  follows:  posts, 
12. 5c.;  caps  and  ties,  lOc.  each.  These  figures  include  not  only 


MINE  TIMBERING  169 

the  framing,  but  also  the  cost  of  unloading  timber  from  the  cars 
at  the  sawmill,  the  cutting  and  squaring,  and  delivery  at  the 
mine. 

The  center  dimensions  of  a  standard  set  are  7ft.  10  in.  by  5x5  ft.; 
giving  a  contents  of  195.75  cu.  ft.  Assume,  for  an  example,  that 
a  set  is  being  put  up  in  ore  carrying  20  per  cent,  galena  (about 
17.3  per  cent,  lead)  with  a  heavy  quartzite  gangue.  The  specific 
gravities  would  be,  approximately,  galena  7.5,  gangue  3.3;  and 
under  these  conditions  it  would  take  about  8.61  cu.  ft.  of  ore  in 
place  (unbroken)  to  make  a  ton.  This  would  give  22.74  tons 
for  the  contents  of  one  square  set.  There  are  parts  of  12  timbers 
in  each  set  — four  posts,  four  caps  and  four  ties  (see  Fig.  123), 
but  only  one-fourth  of  each  of  these  can  be  charged  to  a  single 
set.  This  would  be  equivalent  to  one  post,  one  cap  and  one  tie, 
at  a  total  cost,  for  outside  handling  and  framing,  of  32. 5c.  per  set, 
or  1.429c.  per  ton. 

Especial  attention  is  called  to  the  fact  that  all  of  the  accom- 
panying figures  are  made  from  timbers  actually  in  place. 

In  concluding,  I  wish  to  express  my  thanks  to  Mr.  Stanley  A. 
Easton,  manager,  and  to  Mr.  T.  H.  Simmonds,  superintendent, 
of  the  Bunker  Hill  and  Sullivan  Mining  and  Concentrating  Com- 
pany for  the  assistance  they  gave  me  in  gathering  information. 


TIMBERING   AT   THE   CHILLAGOE   MINES, 
QUEENSLAND  * 

BY  T.  J.  GREENWAY 

IN  working  the  Chillagoe  mines,  in  northern  Queensland,  the 
conditions  are  such  as  render  necessary  the  adoption  of  some 
method  of  square-set  timbering  which  will  permit  of  the  use  of 
the  stunted  and  twisted  local  timber  without  the  aid  of  a  saw- 
mill. After  experimenting  with  various  methods  of  cutting  and 
framing  round  timber,  I  devised  and  adopted  the  method  de- 


Spirit  Level 

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Countersunk 
//  Screws 


Square  Template  with  Spirit  Level 
.for  Gaging  Post  Tensions 


Angle  Template  for  Gaging 
Caps  and  Stretchers 


POST 
Side  View  End  View 

FIGS.  134-137.  —  TEMPLATES  AND  POSTS. 

scribed  hereafter,  which  has  now  been  in  successful  use  for  two 
years. 

The  square  sets  are  made  up  of  the  usual  members,  namely, 
posts,  caps  and  stretchers.  The  shape  of  the  posts  is  shown  in 
Figs.  135  and  137,  and  the  shape  of  the  caps  and  stretchers, 
which  are  alike  in  every  respect,  is  shown  in  Fig.  138.  All  are 

1  From  Engineering  and  Mining  Journal,  March  16,  1905,  Vol.  79. 

170 


MINE  TIMBERING 


171 


cut  from  rough-hewn  logs  which  are  delivered  at  the  various 
mines  by  timber-getters  in  accordance  with  a  specification  re- 
quiring that  the  logs  shall  have  a  clear  minimum  length  of  6  ft. 
6  in.,  and  a  minimum  diameter  of  10  in.  The  heavier  logs  are 
selected  for  making  the  posts,  and  the  lighter  ones  are  used  for 
making  the  caps  and  stretchers. 


CAP  OR  STRETCHER 
Top  View 


CAP  OR  STRETCHER 
Bottom  View 

FIG.  138.  —  CAPS  OR  STRETCHERS. 
10  in.  least  diameter. 

The  various  set  members  are  cut  to  the  required  shapes  and 
dimensions  by  a  simple  method  of  sawing  and  adzing  the  logs, 
accurate  measuring,  centering,  etc.,  being  attained  by  using  the 
miter  box  and  the  angle  and  square  templates  shown  in  Figs.  134, 
136,  and  139. 

A  post  is  made  by  fixing  a  selected  log  in  the  miter  box  (by 
means  of  wooden  wedges)  with  one  rough  end  projecting  out  of 
the  squared  end  of  the  miter  box.  This  rough  end  is  then  cut 
off  flush  with  the  end  of  the  miter  box,  and  the  other  rough  end 
is  cut  off  to  a  length  determined  by  the  transverse  gage  cut  in 
the  miter  box.  The  post,  after  having  been  thus  cut  square  and 
true  to  the  required  length,  is  taken  out  of  the  miter  box  and 
firmly  fixed  in  a  suitable  saw  and  frame,  and  the  ends  are  then 
shaped  into  square  tenons  by  sawing  and  adzing  them  to  dimen- 
sions which  are  gaged  and  squared  by  means  of  the  square  tem- 
plate with  its  accompanying  spirit  level. 


172 


MINE  TIMBERING 


— 1-- 


4- 


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ti 


MINE  TIMBERING 


173 


FIG.  140.  —  METHOD  OF  FRAMING  POSTS,  CAPS,  AND  STRETCHERS. 


174  MINE  TIMBERING 

A  cap  or  stretcher  is  made  by  fixing  a  log  in  the  miter  box, 
and  cutting  it  to  the  length  and  shape  determined  by  the  miter 
cuts.  It  is  then  removed  to  a  sawing  frame,  and  the  beveled 
ends  are  shaped  into  miter  tenons  by  sawing  and  adzing  them  to 
the  required  dimensions,  which  are  determined  by  means  of  the 
angle  template. 

The  manner  of  framing  the  posts,  caps  and  stretchers  together 
underground  is  clearly  shown  in  Fig.  140. 

With  this  method  of  cutting  and  framing,  the  use  of  rough 
log  timber  for  square-set  timbering  presents  no  difficulties.  As 
need  scarcely  be  said,  such  timber  is,  weight  by  weight,  much 
cheaper  and  stronger  than  sawed  timber,  and  it  can  be  used  in 
remote  districts  where  sawed  timber  is  practically  unobtainable. 
In  the  Chillagoe  district  the  logs  are  delivered  at  the  mines  at  a 
cost  of  from  6c.  to  8c.  per  running  foot,  and  the  cost  of  converting 
them  .into  posts,  caps  or  stretchers  is  4c.  per  running  foot. 


TIMBERING   IN  TASMANIA1 
BY  MARK  IRELAND 

THE  orebody  being  worked  at  the  Mount  Rex  tin  mine,  Ben 
Lomond,  Tasmania,  is  about  100  ft.  in  length  by  70  ft.  in  width. 
A  face  of  15  ft.  is  stoped  over  the  whole  level  at  one  operation, 
this  hight  standing  without  any  timber. 

Double  lines  of  logs,  20  ft.  in  length,  and  from  10  in.  to  1  ft. 
thick  at  the  small  end,  are  laid  longitudinally,  butt  to  butt, 
and  breaking  joint  from  end  to  end  of  the  orebody;  they  are  at 
10-ft.  centers  from  wall  to  wall.  The  starting  logs  are  single  for 
the  first  10  ft.,  and  their  ends  are  hitched  into  the  solid  rock. 
These  are  called  "runners/'  and  are  the  logs  which  are  picked  up 
as  the  level  underneath  is  worked  up.  The  double  layer  gives  a 
better  chance  of  picking  up.  Logs  are  then  laid  from  the  center 
of  the  orebody  and  at  right  angles  to  the  runners,  the  ends  being 
hitched  into  the  walls. 

A  space,  7  ft.  wide,  is  left  open  right  through  the  center  of 
the  orebody,  and  a  similar  space  through  from  the  cross-cut  lead- 
ing to  the  shaft.  The  cross  logs  are  spiked  down,  4  ft.  apart, 
to  the  runners.  Decking,  of  small  spars  from  3  to  6  in.  thick,  is 
then  laid  down.  Timber  cribs,  or  "pig-styes,"  are  next  built  up, 
4  ft.  wide,  on  each  side  of  the  open  spaces  previously  referred  to, 
forming  a  skeleton  drive. 

The  pig-styes  are  constructed  as  follows:  Two  logs  are  laid 
parallel,  4  ft.  apart,  and  upon  them,  in  notches  at  the  ends  and 
the  middle,  three  cross  sills  are  laid,  two  more  logs  are  laid  upon 
them  in  turn,  and  so  on  until  7  ft.  high  in  the  clear  is  obtained. 
In  the  spaces  between  the  logs,  waste  rock  is  filled  in  as  fast  as 
built.  Strong  caps,  12-  to  14-in.  timber,  are  then  laid  4  ft.  apart 
across  from  pig-stye  to  pig-stye.  Decking  is  laid  over  these  caps 
as  on  the  level.  Chutes  and  traveling  ways  are  then  built,  and 
1  From  Engineering  and  Mining  Journal,  July  22,  1905,  Vol.  80. 

175 


176  MINE  TIMBERING 

the  level  is  ready  for  filling  with  waste,  which  is  sent  down  from 
the  surface. 

This  method  is  strong,  and  very  cheap  as  compared  with 
square  sets.  But  little  dressing  is  required,  only  an  ax,  saw  and 
auger  being  required;  any  rough,  but  fairly  straight,  timber  will 
do.  An  additional  advantage  is  that  no  blasting,  however  heavy, 
can  injure  it. 


INDEX 


PAGE 

Adit-level 4,  36 

Adits,  definition  of 36 

Alinement  of  inclined-shaft  sets  14 
Anaconda  mine,  Butte,  Mont. .  .  50 

Angle  braces 68,  156 

Atlantic  mine,  Atlantic,  Mich.  .75,  92 

Baltic  mine,  Baltic,  Mich 89,  149 

Barnum  mine,  Ishpeming,  Mich.  93 

Batcheller,  J.  H 150 

Battered  tunnel  sets 164 

Ben  Lomond,  Tasmania 175 

Benches  for  machines 114 

Bingham  Canon 141,  142 

Bingham,  Utah 131,  140 

Boston  and  Montana  mines, 

Butte,  Mont 140 

Boston  Consolidated  mine 141 

British  Columbia,  mining  and 

timbering  in 75 

Bulkheads 70,  140,  161 

"Bunker  Hill  and  Sullivan  Co.'s 

mines  163,  168,  169 

Burlingame  method 51 

Butte,  Mont 140,  141,  142 

Cactus  mine,  Newhouse,  Utah.  .    141 

Calumet  and  Hecla  mines 144 

Campbell,  C.  St.  G 105 

Gates,  Louis  S 131 

Chillagoe  mines,  Queensland.  ...  170 
Chutes,  49, 82, 84, 88, 90, 117, 140,  162 
Comstock  lode,  Virginia  City, 

Nev 20,  51,  55,  56,  141,  142 

Concrete  lining    147 

Copper,  method  of  mining 89 


PAGE 
Cora-Rock  Island  mine,  Butte, 

Mont 142 

Cost  of  timbering  64,  168,  174 

Cralk's  Colusa  mine,  Meaderville, 

Mont 6 

Crane,  W.  R 144 

Creeping  ground  5 

Cribs 16,  41,  68,  114,  175 

Cross-cut,  definition  of 36 

Deidesheimer,  Philip.  .51,  55,  56, 141 

Docks   115 

Drift,  definition  of 36 

Drift  sets 110 

Easton,  Stanley  A 169 

Eureka  method  of  framing.  .  .  .50,  51 

False  sets 7 

Filling,  waste 5,  42,  50,  70,  96 

Forepoling   39 

Four-compartment  shafts 31 

Four-piece  set  10,  12,  38 

Framing,  methods  of 50 

Framing  rectangular  shaft  sets .  .    123 

Georgetown,  California 56 

Girts    38 

Glory-hole  method      86,  93 

Greenway,  T.  J 170 

Halved  framing  for  shaft  sets .  .  13, 18 

Hanging  hooks 15,  23 

Haulage  ways 97,  99 

Heinze,  F.  A.' 142 

Hematite  mine,  Ishpeming,  Mich.     96 


177 


178 


INDEX 


PAGE 

Highland  Boy  mine 141,  143 

Homestake  mine,  Lead,  S.D.    . .    140 

Inclined  shafts 10 

stations  for 13 

Ireland,  Mark 175 

Iron  mining   99,   105 

Ishpeming,   Mich 105 

Knob  Hill  mine,  Phoenix,  B.C.  .     85 

Labor  in  Section  16  mine 119 

Ladders  34,  119 

Lagging   5,   12,  80,  87,   151 

Lake  Superior,  mine  timbering 

at 144 

Lake  Superior  Mining  Co.,  Mich.  105 
Le  Roi  mine,  Rossland,  B.C.  .  .57,  76 

Lead,  S.D 140 

Leadville  mines 140 

Levels,  timbering  of 7,  36,  37 

Loose  ground,  timbering  in .  26, 39, 1 12 

MacDonald,  B 55 

Machines,  method  of  setting  up .  113 

Michigan 75 

Millingmethod 86 

.Mills    116 

Miter  box,  use  of,  in  framing  ...  171 

Mount  Rex  tin  mine,  Tasmania  175 

Mud-sills 78 

Never  Sweat  mine,  Butte,  Mont.       5 

Newhouse,  Samuel 141 

Newhouse,  Utah 141 

Old    Ironsides    mine,    Phoenix, 

B.C. 85 

One-compartment  shafts 20 

Ontario  mine,  Park  City,  Utah.  5 

Open-cut  method 86 

Ophir  mine,  Nevada 51,  55,  56 

Ore  chutes 49 

Ore-skips 12 


Parlee,  N.W. 
Penning     . . . 


75,  101,  102 
41,  45 


PAGE 

Phoenix,  B.C 85 

Pig-styes 175 

Pillars    94,  99,  144 

Plank  lagging 12 

Plumb-bob 14,  24 

Pole  lagging 12 

Pressure  on  timbers 5 

Queen  mine,  Negaunee,  Mich. . .     99 
Queensland 170 

Rectangular  shaft  sets,  framing.    123 

Reinforcing  sets 49 

Repairing  shafts 25 

Rice,  Claude  T 140 

Richmond  method 51 

Rossland,  B.C.,  mines.. 55,  56,  67, 

70,76 

Round  timbers ~*~- 1~ 

Running  ground,  timbering  in.  .     26 

Sanders,  W.  E 3,  123 

Scramming 101 

Section     16     mine,    Ishpeming, 

Mich 94,  105 

Shaft  sets,  locating 22 

rectangular 123 

repairing 25 

Shaft  station  sets 35 

Shaft  timbering 108 

Shafts,  concrete  lining  in 147 

timbering  of 7,  145 

timbering  in  loose  ground     26 
timbering     in      running 

ground    26 

Sill-floor  construction 57,  60 

Simmonds,  T.  H 169 

Single-compartment  shafts 10 

Single-piece  set 37 

Skip-ways 12 

Soft   Ore   Hematite  mine,   Ish- 
peming, Mich 96 

Sollars 119 

Spiling    27,  39 

Spragging 38,  79 

Square-sawed  timber 7 

Square  set,  limitations  of    67 


INDEX 


179 


PAGE 

Square  set,  shaft  timbers 20 

system 106 

timbering,  cost  of  .  .  65 

Square  sets,  in  Section  16  mine.  112 

in  stoping    46 

in  swelling  ground    .  5 
reinforcement  meth- 
ods    68 

Square-shoulder  framing    6 

Staging 118 

Stations    35 

for  inclined  shafts 13 

shaft  sets  for 35 

timbering  of 7 

Step  method  of  excavating    ....  63 

Straight  edge 14,  24,  126 

Stulls 10,  42,  78,  92,  112 

Swelling  ground 5 

Tamarack  mines 144,  147 

Tasmania 175 

Three-compartment  shafts  .  .5,  11,  29 

Three-piece  set 10,  37 

Timber   and    timbering    in    the 

Coeur  d'Alene    150 

Timber,  best  kinds  to  use 150 

chutes 84 

pillars    114 

Timbering,  cost  of    64, 168 

cribbed  shaft 16 

four-compartment 

shafts 31 

in  drifts  and  stopes .  .    147 


PAGE 
Timbering,      levels       in     loose 

ground    39 

principles     of    econ- 
omy in    150 

shafts   20,  108,  145 

in  loose  ground     26 
in         running 
ground    ...     26 

stations 35 

three-compartment 

shafts    29 

two-compartment 

shafts      28 

Tools  used  in  Section  16  mine.  /  119 

Top-slicing 98 

Track  laying 76 

Trimountain  mine  .  . .  . 149 

Tunnel    36 

Two-compartment  shafts  ....11,  28 
Two-piece  set 37 


Utah  Consolidated. 


....    141 


Vertical  shafts 7, 16 

alinement  of    ...     24 

Wages  in  Section  16  mine 119 

Walling-up  system 89 

Waste  filling  .^,.5,  42,  50,  70,  96 

Weight  pressure  on  timbers ....  5 

Winzes 83 

Witwatersrand  goldfields 31 

Working  places,  timbering 41 


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